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1.  Heart-Type Fatty Acid Binding Protein Is an Independent Predictor of Death and Ventricular Dysfunction After Coronary Artery Bypass Graft Surgery 
Anesthesia and analgesia  2010;111(5):1101-1109.
BACKGROUND
Heart-type fatty acid binding protein (hFABP) functions as a myocardial fatty acid transporter and is released into the circulation early after myocardial injury. We hypothesized that hFABP is superior to conventional cardiac biomarkers for predicting early perioperative myocardial injury after coronary artery bypass graft (CABG) surgery.
METHODS
A prospective cohort study of 1298 patients undergoing primary CABG with cardiopulmonary bypass (CPB) was performed at 2 institutions. Four plasma myocardial injury biomarkers (hFABP; cardiac troponin I [cTnI]; creatine kinase, MB [CK-MB] fraction; and myoglobin) were measured at 7 perioperative time points. The association among perioperative cardiac biomarkers and ventricular dysfunction, hospital length of stay (HLOS), and up to 5-year postoperative mortality (median 3.3 years) was assessed using Cox proportional hazard models. We defined in-hospital ventricular dysfunction as a new requirement for 2 or more inotropes, or new placement of an intraaortic balloon pump, or ventricular assist device either during the intraoperative period after the patient separated from CPB or postoperatively in the intensive care unit.
RESULTS
The positive and negative predictive values of mortality for hFABP are 13% (95% confidence interval [CI], 9%–19%) and 95% (95% CI, 94%–96%), respectively, which is higher than for cTnI and CK-MB. After adjusting for clinical predictors, both postoperative day (POD) 1 and peak hFABP levels were independent predictors of ventricular dysfunction (P < 0.0001), HLOS (P < 0.05), and 5-year mortality (P < 0.0001) after CABG surgery. Furthermore, POD1 and peak hFABP levels were significantly superior to other evaluated biomarkers for predicting mortality. In a repeated-measures analysis, hFABP outperformed all other models of fit for HLOS. Patients with POD2 hFABP levels higher than post-CPB hFABP levels had an increased mortality compared with those patients whose POD2 hFABP levels decreased from their post-CPB level (hazard ratio, 10.9; 95% CI, 5.0–23.7; P = 7.2 × 10−10). Mortality in the 120 patients (10%) with a later hFABP peak was 18.3%, compared with 4.7% in those who did not peak later. Alternatively, for cTnI or CK-MB, no difference in mortality was detected.
CONCLUSION
Compared with traditional markers of myocardial injury after CABG surgery, hFABP peaks earlier and is a superior independent predictor of postoperative mortality and ventricular dysfunction.
doi:10.1213/ANE.0b013e3181dd9516
PMCID: PMC3006085  PMID: 20457766
2.  Unprotected left main revascularization in patients with acute coronary syndromes 
European Heart Journal  2009;30(19):2308-2317.
Aims
In acute coronary syndromes (ACS), the optimal revascularization strategy for unprotected left main coronary disease (ULMCD) has been little studied. The objectives of the present study were to describe the practice of ULMCD revascularization in ACS patients and its evolution over an 8-year period, analyse the prognosis of this population and determine the effect of revascularization on outcome.
Methods and results
Of 43 018 patients enrolled in the Global Registry of Acute Coronary Events (GRACE) between 2000 and 2007, 1799 had significant ULMCD and underwent percutaneous coronary intervention (PCI) alone (n = 514), coronary artery bypass graft (CABG) alone (n = 612), or no revascularization (n = 673). Mortality was 7.7% in hospital and 14% at 6 months. Over the 8-year study, the GRACE risk score remained constant, but there was a steady shift to more PCI than CABG over time. Patients undergoing PCI presented more frequently with ST-segment elevation myocardial infarction (STEMI), after cardiac arrest, or in cardiogenic shock; 48% of PCI patients underwent revascularization on the day of admission vs. 5.1% in the CABG group. After adjustment, revascularization was associated with an early hazard of hospital death vs. no revascularization, significant for PCI (hazard ratio (HR) 2.60, 95% confidence interval (CI) 1.62–4.18) but not for CABG (1.26, 0.72–2.22). From discharge to 6 months, both PCI (HR 0.45, 95% CI 0.23–0.85) and CABG (0.11, 0.04–0.28) were significantly associated with improved survival in comparison with an initial strategy of no revascularization. Coronary artery bypass graft revascularization was associated with a five-fold increase in stroke compared with the other two groups.
Conclusion
Unprotected left main coronary disease in ACS is associated with high mortality, especially in patients with STEMI and/or haemodynamic or arrhythmic instability. Percutaneous coronary intervention is now the most common revascularization strategy and preferred in higher risk patients. Coronary artery bypass graft is often delayed and performed in lower risk patients, leading to good 6-month survival. The two approaches therefore appear complementary.
doi:10.1093/eurheartj/ehp353
PMCID: PMC2755115  PMID: 19720640
Left main disease; Acute coronary syndrome
3.  Enhanced External Counterpulsation (EECP) 
Executive Summary
Objective
To assess the effectiveness, and cost effectiveness of EECP in patients with severe anginal symptoms, secondary to chronic coronary disease, who are unresponsive to exhaustive pharmacotherapy and not candidates for surgical/percutaneous revascularization procedures (e.g., angioplasty, coronary bypass surgery).
To assess the effectiveness, and cost effectiveness of EECP in patients with heart failure.
Clinical Need
Angina
Angina is a clinical syndrome characterized by discomfort in the chest, jaw, shoulder, back or arm. Angina usually occurs in patients with coronary artery disease (CAD) involving ≥1 large epicardial artery. However it can also occur in people with valvular heart disease, hypertrophic cardiomyopathy, and uncontrolled hypertension.
Conventional approaches to restoring the balance between oxygen supply and demand focus on the disruption of the underlying disease through: drug therapy (β blockers, calcium channel blockers, nitrates, antiplatelet agents, ACE inhibitors, statins); life-style modifications (smoking cessation, weight loss); or revascularization techniques such as coronary artery bypass graft surgery (CABG) or percutaneous coronary interventions (PCI). (1) Limitations of each of these approaches include: adverse drug effects, procedure-related mortality and morbidity, restenosis after PCI, and time dependent graft attrition after CABG. Furthermore, an increasing number of patients are not appropriate candidates for standard revascularization options, due to co-morbid conditions (HF, peripheral vascular disease), poor distal coronary artery targets, and patient preference. The morbidity and mortality associated with repeat surgical revascularization procedures are significantly higher, and often excludes these patients from consideration for further revascularizations. (2)
Patients with CAD who have chronic ischemic symptoms that are unresponsive to both conventional medical therapy and revascularization techniques have refractory angina pectoris. It has been estimated that greater than 100,000 patients each year in the US may be diagnosed as having this condition. (3) Patients with refractory angina have marked limitation of ordinary physical activity or are unable to perform any ordinary physical activity without discomfort (CCS functional class III/IV). Also, there must be some objective evidence of ischemia as demonstrated by exercise treadmill testing, stress imaging studies or coronary physiologic studies. (1)
Dejongste et al. (4)estimated that the prevalence of chronic refractory angina is about 100,000 patients in the United States. This would correspond to approximately 3,800 (100,000 x 3.8% [Ontario is approximately 3.8% of the population of the United States]) patients in Ontario having chronic refractory angina.
Heart Failure
Heart failure results from any structural or functional cardiac disorder that impairs the ability of the heart to act as a pump.
A recent study (5) revealed 28,702 patients were hospitalized for first-time HF in Ontario between April 1994 and March 1997. Women comprised 51% of the cohort. Eighty-five percent were aged 65 years or older, and 58% were aged 75 years or older.
Patients with chronic HF experience shortness of breath, a limited capacity for exercise, high rates of hospitalization and rehospitalization, and die prematurely. (6) The New York Heart Association (NYHA) has provided a commonly used functional classification for the severity of HF (7):
Class I: No limitation of physical activity. No symptoms with ordinary exertion.
Class II: Slight limitations of physical activity. Ordinary activity causes symptoms.
Class III: Marked limitation of physical activity. Less than ordinary activity causes symptoms. Asymptomatic at rest.
Class IV: Inability to carry out any physical activity without discomfort. Symptoms at rest.
The National Heart, Lung, and Blood Institute (7) estimates that 35% of patients with HF are in functional NYHA class I; 35% are in class II; 25%, class III; and 5%, class IV. Surveys (8) suggest that from 5% to 15% of patients with HF have persistent severe symptoms, and that the remainder of patients with HF is evenly divided between those with mild and moderately severe symptoms.
To date, the diagnosis and management of chronic HF has concentrated on patients with the clinical syndrome of HF accompanied by severe left ventricular systolic dysfunction. Major changes in treatment have resulted from a better understanding of the pathophysiology of HF and the results of large clinical trials. Treatment for chronic HF includes lifestyle management, drugs, cardiac surgery, or implantable pacemakers and defibrillators. Despite pharmacologic advances, which include diuretics, angiotensin-converting enzyme inhibitors, beta-blockers, spironolactone, and digoxin, many patients remain symptomatic on maximally tolerated doses. (6)
The Technology
Patients are typically treated by a trained technician in a medically supervised environment for 1 hour daily for a total of 35 hours over 7 weeks. The procedure involves sequential inflation and deflation of compressible cuffs wrapped around the patient’s calves, lower thighs and upper thighs. In addition to 3 sets of cuffs, the patient has finger plethysmogram and electrocardiogram (ECG) attachments that are connected to a control and display console.
External counterpulsation was used in the United States to treat cardiogenic shock after acute myocardial infarction. (9;10) More recently, an enhanced version namely “enhanced external counterpulsation” (EECP) was introduced as a noninvasive procedure for outpatient treatment of patients with severe, uncontrollable cardiac ischemia. EECP is said to increase coronary perfusion pressure and reduce the myocardial oxygen demand. Currently, EECP is not applicable for all patients with refractory angina pectoris. For example, many patients are considered ineligible for therapy due to co-morbidities, including those with severe pulmonary vascular disease, deep vein thrombosis, phlebitis and irregular heart rhythms, and heart failure. (1)
Very recently, investigation began into EECP as an adjunctive treatment for patients with HF. Anecdotal reports suggested that EECP may benefit patients with coronary disease and left ventricular dysfunction. The safety and effectiveness of EECP in patients with symptomatic heart failure and coronary disease and its role in patients with nonischemic heart failure secondary to LV dysfunction is unclear. Furthermore, the safety and effectiveness of EECP in the different stages of HF and whether it is only for patients who are refractive to pharmacotherapy is unknown.
2003 Health Technology Assessment by the Medical Advisory Secretariat
The Medical Advisory Secretariat health technology assessment (originally published in February 2003) reported on the effectiveness of EECP for patients with angina and HF. The report concluded that there was insufficient evidence to support the use of EECP in patients with refractory stable CCS III/IV angina as well as insufficient evidence to support the use of EECP in patients with HF.
Review Strategy
The aim of this literature review was to assess the effectiveness, safety, and cost effectiveness of EECP for the treatment of refractory stable CCS III/IV angina or HF.
The standard search strategy used by the Medical Advisory Secretariat was used. This included a search of all international health technology assessments as well as a search of the medical literature from December 2002 to March 2006.
A modification of the GRADE approach (11) was used to make judgments about the quality of evidence and strength of recommendations systematically and explicitly. GRADE provides a framework for structured reflection and can help to ensure that appropriate judgments are made. GRADE takes into account a study’s design, quality, consistency, and directness in judging the quality of evidence for each outcome. The balance between benefits and harms, quality of evidence, applicability, and the certainty of the baseline risks are considered in judgments about the strength of recommendations.
Summary of Findings
The Cochrane and INAHTA databases yielded 3 HTAs or systematic reviews on EECP treatment (Blue Cross Blue Shield Technology Evaluation Center [BCBS TEC], ECRI, and the Centers for Medicare and Medicaid Services [CMS]). A search of Medline and Embase December 2005 – March 2006 (after the literature search cutoff from the most recent HTA) was conducted using key words enhanced external counterpulsation, EECP, angina, myocardial ischemia, congestive heart failure. This search produced 1 study which met the inclusion criteria. This level 4a study was inferior in quality to the RCT which formed the basis of the 2003 Medical Advisory Secretariat recommendation.
BCBS reviewed the evidence through November 2005 to determine if EECP improves health outcomes for refractory chronic stable angina pectoris or chronic stable HF. (12) BCBS concluded that the available evidence is not sufficient to permit conclusions of the effect of EECP on health outcomes. Both controlled trials had methodologic flaws (MUST EECP and MUST EECP quality of life studies). The case series and observational studies for both indications while suggestive of a treatment benefit from EECP have shortcomings as well.
On March 20 2006, CMS posted their proposed coverage decision memorandum for external counterpulsation therapy. (13) Overall, CMS stated that the evidence is not adequate to conclude that external counterpulsation therapy is reasonable and necessary for:
Canadian Cardiovascular Society Classification (CCSC) II angina
Heart failure
NYHA class II/III stable HF symptoms with an EF≤35%
NYHA class II/III stable HF symptoms with an EF≤40%
NYHA class IV HF
Acute HF
Cardiogenic shock
Acute MI
In January 2005, ECRI (14) stated that there was insufficient evidence available to draw conclusions about the long-term effectiveness of EECP, with respect to morbidity, survival, or quality of life, for any coronary indication (refractory angina, congestive heart failure, cardiogenic shock and acute MI).
GRADE Quality of the Studies
According to the GRADE Working Group criteria, the quality of the trials was examined (Table 1). (11)
Quality refers to the criteria such as the adequacy of allocation concealment, blinding and followup.
Consistency refers to the similarity of estimates of effect across studies. If there is important unexplained inconsistency in the results, our confidence in the estimate of effect for that outcome decreases. Differences in the direction of effect, the size of the differences in effect and the significance of the differences guide the decision about whether important inconsistency exists.
Directness refers to the extent to which the people interventions and outcome measures are similar to those of interest. For example, there may be uncertainty about the directness of the evidence if the people of interest are older, sicker or have more comorbidity than those in the studies.
As stated by the GRADE Working Group, the following definitions were used in grading the quality of the evidence. (11)
GRADE Quality of Studies
Economic Analysis - Literature Review
No economic analysis of EECP was identified in the published literature.
Estimated Prevalence of Angina in Ontario
3,800 patients with chronic refractory angina:
The number of patients with chronic refractory angina in the US is estimated to be approximately 100,000 (4), this corresponds to about 3,800 patients in Ontario (3.8% × 100,000) with refractory angina.
3,800 patients × $7,000 Cdn (approximate cost for a full course of therapy) ~ $26.6M Cdn.
Estimated Prevalence of Heart Failure in Ontario
23,700 patients EF ≤ 0.35:
This estimate is from an expert (personal communication) at the Institute for Clinical Evaluative Sciences (ICES), where they examined a sample of echocardiography studies drawn from a diagnostic lab in 2001. They found that the prevalence of EF ≤ 0.35 was 8.3%, and if generalized to all patients undergoing echocardiography, there would be 23,700 patients.
23,700 patients with EF ≤35% × $7,000 Cdn ~ $166 M Cdn.
Conclusions
There is insufficient evidence to support the effectiveness and safety of EECP treatment for patients with refractory stable CCS III-IV angina or HF.
As per the GRADE Working Group, overall recommendations consider 4 main factors. (11)
The tradeoffs, taking into account the estimated size of the effect for the main outcome, the confidence limits around those estimates and the relative value placed on the outcome.
The quality of the evidence.
Translation of the evidence into practice in a specific setting, taking into consideration important factors that could be expected to modify the size of the expected effects such as proximity to a hospital or availability of necessary expertise.
Uncertainty about the baseline risk for the population of interest.
The GRADE Working Group also recommends that incremental costs of healthcare alternatives should be considered explicitly alongside the expected health benefits and harms. (11) Recommendations rely on judgments about the value of the incremental health benefits in relation to the incremental costs. The last column in Table 2 is the overall trade-off between benefits and harms and incorporates any risk/uncertainty.
For angina and heart failure, the overall GRADE and strength of the recommendations is “weak” – the quality of the evidence is “low” (uncertainties due to methodological limitations in the study design in terms of study quality and directness), and the corresponding risk/uncertainty is increased due to a budget impact of approximately $26.6 M Cdn or $166 M Cdn respectively while the cost-effectiveness of EECP is unknown and difficult to estimate considering that there are no high quality studies of effectiveness.
Overall GRADE and Strength of Recommendation (Including Uncertainty)
PMCID: PMC3379533  PMID: 23074496
4.  Coronary artery bypass grafting or percutaneous revascularization in acute myocardial infarction? 
A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was as follows: is coronary artery bypass graft (CABG) surgery superior to percutaneous coronary intervention (PCI) in terms of in-hospital mortality and morbidity and long-term outcomes in patients with acute myocardial infarction (MI)? A total of 104 papers were returned using the selected search. Of these, six represented the best evidence to answer the clinical question. The selection criteria were comparative studies with only PCI and CABG groups in patients with acute MI. Case reports, reviews, recommendations and studies on a specific population or out of the context of acute MI were excluded. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Almost all PCI patients received stents. One study used drug-eluting stents (DES). Two randomized studies showed similar short- and mid-term morbidities and mortalities in patients with acute MI in the PCI and CABG groups but higher repeat revascularization rates after PCI. Three observational studies found comparable survival, but one of them found more periprocedural events with CABG and the other two found more recurrent ischaemia requiring repeat revascularization in the PCI group. In one cohort study, CABG appeared to be an independent risk factor for death in N-STEMI according to the European Society/American College of Cardiology 2000 definition. The results are strongly influenced by the definition of acute MI. In an institution offering the two techniques with an equivalent accessibility, the principal advantage of PCI is a lower incidence of periprocedural and short-term morbidities. CABG, on the other hand, offers a better durability with less mid-term repeat revascularization required, especially when compared with PCI with DES implantation. Choice had to weight up coronary artery anatomy, number and localization of coronary artery stenosis and accessibility of both PCI and CABG treatments. Medical and surgical discussion within the Heart Team is required to make the best medical decision for each patient.
doi:10.1093/icvts/ivt381
PMCID: PMC3829498  PMID: 23962854
Review; Coronary artery bypass; Myocardial infarction; Coronary disease
5.  Three-Year Outcomes of Multivessel Revascularization in Very Elderly Acute Coronary Syndrome Patients 
The Annals of thoracic surgery  2010;89(6):1889-1895.
Background
Comparative effectiveness of interventional treatment strategies for the very elderly with acute coronary syndrome remains poorly defined due to study exclusions. Interventions include percutaneous coronary intervention (PCI), usually with stents, or coronary artery bypass grafting (CABG). The elderly are frequently directed to PCI because of provider perceptions that PCI is at therapeutic equipoise with CABG and that CABG incurs increased risk. We evaluated long-term outcomes of CABG versus PCI in a cohort of very elderly Medicare beneficiaries presenting with acute coronary syndrome.
Methods
Using Medicare claims data, we analyzed outcomes of multivessel PCI or CABG treatment for a cohort of 10,141 beneficiaries age 85 and older diagnosed with acute coronary syndrome in 2003 and 2004. The cohort was followed for survival and composite outcomes (death, repeat revascularization, stroke, acute myocardial infarction) for three years. Logistic regressions controlled for patient demographics and comorbidities with propensity score adjustment for procedure selection.
Results
Percutaneous coronary intervention showed early benefits of lesser morbidity and mortality, but CABG outcomes improved relative to PCI outcomes by three years (p < 0.01). At 36 months post-initial revascularization, 66.0% of CABG recipients survived (versus 62.7% of PCI recipients, p < 0.05) and 46.1% of CABG recipients were free from composite outcome (versus 38.7% of PCI recipients, p < 0.01).
Conclusions
In very elderly patients with ACS and multivessel CAD, CABG appears to offer an advantage over PCI of survival and freedom from composite endpoint at three years. Optimizing the benefit of CABG in very elderly patients requires absence of significant congestive heart failure, lung disease, and peripheral vascular disease.
doi:10.1016/j.athoracsur.2010.03.003
PMCID: PMC2908496  PMID: 20494044
6.  Positron Emission Tomography for the Assessment of Myocardial Viability 
Executive Summary
In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability, an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients undergoing viability assessment. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities.
After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies that can be used for the assessment of myocardial viability: positron emission tomography, cardiac magnetic resonance imaging, dobutamine echocardiography, and dobutamine echocardiography with contrast, and single photon emission computed tomography.
A 2005 review conducted by MAS determined that positron emission tomography was more sensitivity than dobutamine echocardiography and single photon emission tomography and dominated the other imaging modalities from a cost-effective standpoint. However, there was inadequate evidence to compare positron emission tomography and cardiac magnetic resonance imaging. Thus, this report focuses on this comparison only. For both technologies, an economic analysis was also completed.
The Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html
Positron Emission Tomography for the Assessment of Myocardial Viability: An Evidence-Based Analysis
Magnetic Resonance Imaging for the Assessment of Myocardial Viability: An Evidence-Based Analysis
Objective
The objective of this analysis is to assess the effectiveness and safety of positron emission tomography (PET) imaging using F-18-fluorodeoxyglucose (FDG) for the assessment of myocardial viability. To evaluate the effectiveness of FDG PET viability imaging, the following outcomes are examined:
the diagnostic accuracy of FDG PET for predicting functional recovery;
the impact of PET viability imaging on prognosis (mortality and other patient outcomes); and
the contribution of PET viability imaging to treatment decision making and subsequent patient outcomes.
Clinical Need: Condition and Target Population
Left Ventricular Systolic Dysfunction and Heart Failure
Heart failure is a complex syndrome characterized by the heart’s inability to maintain adequate blood circulation through the body leading to multiorgan abnormalities and, eventually, death. Patients with heart failure experience poor functional capacity, decreased quality of life, and increased risk of morbidity and mortality.
In 2005, more than 71,000 Canadians died from cardiovascular disease, of which, 54% were due to ischemic heart disease. Left ventricular (LV) systolic dysfunction due to coronary artery disease (CAD)1 is the primary cause of heart failure accounting for more than 70% of cases. The prevalence of heart failure was estimated at one percent of the Canadian population in 1989. Since then, the increase in the older population has undoubtedly resulted in a substantial increase in cases. Heart failure is associated with a poor prognosis: one-year mortality rates were 32.9% and 31.1% for men and women, respectively in Ontario between 1996 and 1997.
Treatment Options
In general, there are three options for the treatment of heart failure: medical treatment, heart transplantation, and revascularization for those with CAD as the underlying cause. Concerning medical treatment, despite recent advances, mortality remains high among treated patients, while, heart transplantation is affected by the limited availability of donor hearts and consequently has long waiting lists. The third option, revascularization, is used to restore the flow of blood to the heart via coronary artery bypass grafting (CABG) or through minimally invasive percutaneous coronary interventions (balloon angioplasty and stenting). Both methods, however, are associated with important perioperative risks including mortality, so it is essential to properly select patients for this procedure.
Myocardial Viability
Left ventricular dysfunction may be permanent if a myocardial scar is formed, or it may be reversible after revascularization. Reversible LV dysfunction occurs when the myocardium is viable but dysfunctional (reduced contractility). Since only patients with dysfunctional but viable myocardium benefit from revascularization, the identification and quantification of the extent of myocardial viability is an important part of the work-up of patients with heart failure when determining the most appropriate treatment path. Various non-invasive cardiac imaging modalities can be used to assess patients in whom determination of viability is an important clinical issue, specifically:
dobutamine echocardiography (echo),
stress echo with contrast,
SPECT using either technetium or thallium,
cardiac magnetic resonance imaging (cardiac MRI), and
positron emission tomography (PET).
Dobutamine Echocardiography
Stress echocardiography can be used to detect viable myocardium. During the infusion of low dose dobutamine (5 – 10 μg/kg/min), an improvement of contractility in hypokinetic and akentic segments is indicative of the presence of viable myocardium. Alternatively, a low-high dose dobutamine protocol can be used in which a biphasic response characterized by improved contractile function during the low-dose infusion followed by a deterioration in contractility due to stress induced ischemia during the high dose dobutamine infusion (dobutamine dose up to 40 ug/kg/min) represents viable tissue. Newer techniques including echocardiography using contrast agents, harmonic imaging, and power doppler imaging may help to improve the diagnostic accuracy of echocardiographic assessment of myocardial viability.
Stress Echocardiography with Contrast
Intravenous contrast agents, which are high molecular weight inert gas microbubbles that act like red blood cells in the vascular space, can be used during echocardiography to assess myocardial viability. These agents allow for the assessment of myocardial blood flow (perfusion) and contractile function (as described above), as well as the simultaneous assessment of perfusion to make it possible to distinguish between stunned and hibernating myocardium.
SPECT
SPECT can be performed using thallium-201 (Tl-201), a potassium analogue, or technetium-99 m labelled tracers. When Tl-201 is injected intravenously into a patient, it is taken up by the myocardial cells through regional perfusion, and Tl-201 is retained in the cell due to sodium/potassium ATPase pumps in the myocyte membrane. The stress-redistribution-reinjection protocol involves three sets of images. The first two image sets (taken immediately after stress and then three to four hours after stress) identify perfusion defects that may represent scar tissue or viable tissue that is severely hypoperfused. The third set of images is taken a few minutes after the re-injection of Tl-201 and after the second set of images is completed. These re-injection images identify viable tissue if the defects exhibit significant fill-in (> 10% increase in tracer uptake) on the re-injection images.
The other common Tl-201 viability imaging protocol, rest-redistribution, involves SPECT imaging performed at rest five minutes after Tl-201 is injected and again three to four hours later. Viable tissue is identified if the delayed images exhibit significant fill-in of defects identified in the initial scans (> 10% increase in uptake) or if defects are fixed but the tracer activity is greater than 50%.
There are two technetium-99 m tracers: sestamibi (MIBI) and tetrofosmin. The uptake and retention of these tracers is dependent on regional perfusion and the integrity of cellular membranes. Viability is assessed using one set of images at rest and is defined by segments with tracer activity greater than 50%.
Cardiac Magnetic Resonance Imaging
Cardiac magnetic resonance imaging (cardiac MRI) is a non-invasive, x-ray free technique that uses a powerful magnetic field, radio frequency pulses, and a computer to produce detailed images of the structure and function of the heart. Two types of cardiac MRI are used to assess myocardial viability: dobutamine stress magnetic resonance imaging (DSMR) and delayed contrast-enhanced cardiac MRI (DE-MRI). DE-MRI, the most commonly used technique in Ontario, uses gadolinium-based contrast agents to define the transmural extent of scar, which can be visualized based on the intensity of the image. Hyper-enhanced regions correspond to irreversibly damaged myocardium. As the extent of hyper-enhancement increases, the amount of scar increases, so there is a lower the likelihood of functional recovery.
Cardiac Positron Emission Tomography
Positron emission tomography (PET) is a nuclear medicine technique used to image tissues based on the distinct ways in which normal and abnormal tissues metabolize positron-emitting radionuclides. Radionuclides are radioactive analogs of common physiological substrates such as sugars, amino acids, and free fatty acids that are used by the body. The only licensed radionuclide used in PET imaging for viability assessment is F-18 fluorodeoxyglucose (FDG).
During a PET scan, the radionuclides are injected into the body and as they decay, they emit positively charged particles (positrons) that travel several millimetres into tissue and collide with orbiting electrons. This collision results in annihilation where the combined mass of the positron and electron is converted into energy in the form of two 511 keV gamma rays, which are then emitted in opposite directions (180 degrees) and captured by an external array of detector elements in the PET gantry. Computer software is then used to convert the radiation emission into images. The system is set up so that it only detects coincident gamma rays that arrive at the detectors within a predefined temporal window, while single photons arriving without a pair or outside the temporal window do not active the detector. This allows for increased spatial and contrast resolution.
Evidence-Based Analysis
Research Questions
What is the diagnostic accuracy of PET for detecting myocardial viability?
What is the prognostic value of PET viability imaging (mortality and other clinical outcomes)?
What is the contribution of PET viability imaging to treatment decision making?
What is the safety of PET viability imaging?
Literature Search
A literature search was performed on July 17, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2004 to July 16, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. In addition, published systematic reviews and health technology assessments were reviewed for relevant studies published before 2004. Reference lists of included studies were also examined for any additional relevant studies not already identified. The quality of the body of evidence was assessed as high, moderate, low or very low according to GRADE methodology.
Inclusion Criteria
Criteria applying to diagnostic accuracy studies, prognosis studies, and physician decision-making studies:
English language full-reports
Health technology assessments, systematic reviews, meta-analyses, randomized controlled trials (RCTs), and observational studies
Patients with chronic, known CAD
PET imaging using FDG for the purpose of detecting viable myocardium
Criteria applying to diagnostic accuracy studies:
Assessment of functional recovery ≥3 months after revascularization
Raw data available to calculate sensitivity and specificity
Gold standard: prediction of global or regional functional recovery
Criteria applying to prognosis studies:
Mortality studies that compare revascularized patients with non-revascularized patients and patients with viable and non-viable myocardium
Exclusion Criteria
Criteria applying to diagnostic accuracy studies, prognosis studies, and physician decision-making studies:
PET perfusion imaging
< 20 patients
< 18 years of age
Patients with non-ischemic heart disease
Animal or phantom studies
Studies focusing on the technical aspects of PET
Studies conducted exclusively in patients with acute myocardial infarction (MI)
Duplicate publications
Criteria applying to diagnostic accuracy studies
Gold standard other than functional recovery (e.g., PET or cardiac MRI)
Assessment of functional recovery occurs before patients are revascularized
Outcomes of Interest
Diagnostic accuracy studies
Sensitivity and specificity
Positive and negative predictive values (PPV and NPV)
Positive and negative likelihood ratios
Diagnostic accuracy
Adverse events
Prognosis studies
Mortality rate
Functional status
Exercise capacity
Quality of Life
Influence on PET viability imaging on physician decision making
Statistical Methods
Pooled estimates of sensitivity and specificity were calculated using a bivariate, binomial generalized linear mixed model. Statistical significance was defined by P values less than 0.05, where “false discovery rate” adjustments were made for multiple hypothesis testing. Using the bivariate model parameters, summary receiver operating characteristic (sROC) curves were produced. The area under the sROC curve was estimated by numerical integration with a cubic spline (default option). Finally, pooled estimates of mortality rates were calculated using weighted means.
Quality of Evidence
The quality of evidence assigned to individual diagnostic studies was determined using the QUADAS tool, a list of 14 questions that address internal and external validity, bias, and generalizibility of diagnostic accuracy studies. Each question is scored as “yes”, “no”, or “unclear”. The quality of the body of evidence was then assessed as high, moderate, low, or very low according to the GRADE Working Group criteria. The following definitions of quality were used in grading the quality of the evidence:
Summary of Findings
A total of 40 studies met the inclusion criteria and were included in this review: one health technology assessment, two systematic reviews, 22 observational diagnostic accuracy studies, and 16 prognosis studies. The available PET viability imaging literature addresses two questions: 1) what is the diagnostic accuracy of PET imaging for the assessment; and 2) what is the prognostic value of PET viability imaging. The diagnostic accuracy studies use regional or global functional recovery as the reference standard to determine the sensitivity and specificity of the technology. While regional functional recovery was most commonly used in the studies, global functional recovery is more important clinically. Due to differences in reporting and thresholds, however, it was not possible to pool global functional recovery.
Functional recovery, however, is a surrogate reference standard for viability and consequently, the diagnostic accuracy results may underestimate the specificity of PET viability imaging. For example, regional functional recovery may take up to a year after revascularization depending on whether it is stunned or hibernating tissue, while many of the studies looked at regional functional recovery 3 to 6 months after revascularization. In addition, viable tissue may not recover function after revascularization due to graft patency or re-stenosis. Both issues may lead to false positives and underestimate specificity. Given these limitations, the prognostic value of PET viability imaging provides the most direct and clinically useful information. This body of literature provides evidence on the comparative effectiveness of revascularization and medical therapy in patients with viable myocardium and patients without viable myocardium. In addition, the literature compares the impact of PET-guided treatment decision making with SPECT-guided or standard care treatment decision making on survival and cardiac events (including cardiac mortality, MI, hospital stays, unintended revascularization, etc).
The main findings from the diagnostic accuracy and prognosis evidence are:
Based on the available very low quality evidence, PET is a useful imaging modality for the detection of viable myocardium. The pooled estimates of sensitivity and specificity for the prediction of regional functional recovery as a surrogate for viable myocardium are 91.5% (95% CI, 88.2% – 94.9%) and 67.8% (95% CI, 55.8% – 79.7%), respectively.
Based the available very low quality of evidence, an indirect comparison of pooled estimates of sensitivity and specificity showed no statistically significant difference in the diagnostic accuracy of PET viability imaging for regional functional recovery using perfusion/metabolism mismatch with FDG PET plus either a PET or SPECT perfusion tracer compared with metabolism imaging with FDG PET alone.
FDG PET + PET perfusion metabolism mismatch: sensitivity, 89.9% (83.5% – 96.4%); specificity, 78.3% (66.3% – 90.2%);
FDG PET + SPECT perfusion metabolism mismatch: sensitivity, 87.2% (78.0% – 96.4%); specificity, 67.1% (48.3% – 85.9%);
FDG PET metabolism: sensitivity, 94.5% (91.0% – 98.0%); specificity, 66.8% (53.2% – 80.3%).
Given these findings, further higher quality studies are required to determine the comparative effectiveness and clinical utility of metabolism and perfusion/metabolism mismatch viability imaging with PET.
Based on very low quality of evidence, patients with viable myocardium who are revascularized have a lower mortality rate than those who are treated with medical therapy. Given the quality of evidence, however, this estimate of effect is uncertain so further higher quality studies in this area should be undertaken to determine the presence and magnitude of the effect.
While revascularization may reduce mortality in patients with viable myocardium, current moderate quality RCT evidence suggests that PET-guided treatment decisions do not result in statistically significant reductions in mortality compared with treatment decisions based on SPECT or standard care protocols. The PARR II trial by Beanlands et al. found a significant reduction in cardiac events (a composite outcome that includes cardiac deaths, MI, or hospital stay for cardiac cause) between the adherence to PET recommendations subgroup and the standard care group (hazard ratio, .62; 95% confidence intervals, 0.42 – 0.93; P = .019); however, this post-hoc sub-group analysis is hypothesis generating and higher quality studies are required to substantiate these findings.
The use of FDG PET plus SPECT to determine perfusion/metabolism mismatch to assess myocardial viability increases the radiation exposure compared with FDG PET imaging alone or FDG PET combined with PET perfusion imaging (total-body effective dose: FDG PET, 7 mSv; FDG PET plus PET perfusion tracer, 7.6 – 7.7 mSV; FDG PET plus SPECT perfusion tracer, 16 – 25 mSv). While the precise risk attributed to this increased exposure is unknown, there is increasing concern regarding lifetime multiple exposures to radiation-based imaging modalities, although the incremental lifetime risk for patients who are older or have a poor prognosis may not be as great as for healthy individuals.
PMCID: PMC3377573  PMID: 23074393
7.  The efficacies of modified mechanical post conditioning on myocardial protection for patients undergoing coronary artery bypass grafting 
Background
Coronary artery bypass grafting (CABG) with cardioplegic cardiac arrest and cardiopulmonary bypass (CPB) is associated with myocardial injury. The aim of this study was to investigate whether a modified mechanical post-conditioning (MMPOC) technique has a myocardial protective effect by enhancing early metabolic recovery of the heart following revascularization.
Methods
A prospective, randomized trial was conducted at a single-center university hospital performing adult cardiac surgery. Seventy-nine adult patients undergoing first-time elective isolated multivessel coronary artery bypass grafting were prospectively randomized to MMPOC or control group. Anesthetic, cardiopulmonary bypass, myocardial protection, and surgical techniques were standardized. The post reperfusion cardiac indices, inotrope use and biochemical-electrocardiographic evidence of myocardial injury were recorded. The incidence of postoperative complications was recorded prospectively.
Results
Operative characteristics, including CPB and aortic cross-clamp time, were similar between the two groups (p>0.05). The MMPOC group had lower troponin I and other cardiac biomarkers level post CPB and postoperatively, with greater improvement in cardiac indices (p<0.001). MMPOC shortened post surgery hospitalization from 9.1 ± 2.1 to 7.5 ± 1.6 days (p<0.001).
Conclusions
MMPOC technique promotes early metabolic recovery of the heart during elective CABG, leading to better myocardial protection and functional recovery.
doi:10.1186/1749-8090-7-73
PMCID: PMC3494583  PMID: 22877317
Cardiopulmonary bypass; Myocardial protection; Ischemia-reperfusion injury; Coronary artery bypass grafting; Post-conditioning
8.  Optimal Choice of Coronary Revascularization and Stent Type in Diabetic Patients with Coronary Artery Disease 
Cardiology and Therapy  2013;2(1):69-84.
Patients with diabetes mellitus (DM) are prone to a diffuse and accelerated form of coronary artery disease (CAD), which in turn is a major cause of cardiac-related morbidity and mortality. Compared with patients without diabetes, patients with diabetes undergoing coronary revascularization are at higher risk of procedural, short-, and long-term cardiovascular events and mortality. Although coronary artery bypass grafting (CABG) has been regarded as the primary revascularization strategy in diabetic patients with complex CAD, percutaneous coronary intervention (PCI) is an effective revascularization alternative, due to remarkable advances in stent devices and adjunctive drug therapies. Outcomes data, from subgroup analyses and small-sized clinical trials and large registries, have suggested that PCI with current stent technology showed comparable long-term risks of mortality and hard endpoints, but higher risk of repeat revascularization for the diabetic population compared to CABG. However, the recent landmark International Future REvascularization Evaluation in patients with diabetes mellitus: optimal management of Multivessel disease (FREEDOM) trial provides compelling evidence of the superiority of CABG over PCI in reducing the rates of death, myocardial infarction, at the expense of stroke, in patients with diabetes with advanced CAD. When opting for PCI in patients with diabetes, currently used drug-eluting stents (DES) are more efficient in reducing the risk of repeat revascularization without compromising safety outcomes, compared to bare-metal stents. The selection of a specific type of DES in patients with diabetes is controversial and therefore more data comparing second- and newer-generation DES for patients with diabetes are currently needed. Also, efforts to make more advanced DES platforms suitable for patients with diabetes with complicated angiographic features are still ongoing.
doi:10.1007/s40119-013-0014-3
PMCID: PMC4107438  PMID: 25135290
Coronary artery bypass grafting; Coronary artery disease; Diabetes mellitus; Drug-eluting stents; Percutaneous coronary intervention
9.  Percutaneous Coronary Intervention Versus Coronary Artery Bypass Grafting in Patients with Coronary Artery Disease and Diabetic Nephropathy: A Single Center Experience 
Background
Patients with diabetic nephropathy (DN) and coronary artery disease (CAD) represent a subset of patients with high cardiovascular morbidity and mortality. The optimal revascularization strategy using either percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) remains controversial. The purpose of this study was to compare the clinical outcomes of PCI to CABG in DN patients with CAD.
Methods
The clinical and angiographic records of DN patients with CAD who underwent either CABG (n=52) or PCI (n=48) were retrospectively analyzed.
Results
The baseline characteristics were similar in the two groups except for the severity of the CAD. At 30 days, the death rate (PCI: 2.1% vs. CABG: 9.6%, p=0.21) and major adverse cardiac events (MACE) rate (PCI: 2.1% vs. CABG: 9.6%, p=0.21) were similar in comparisons between the PCI and CABG groups. At three years, the death rate (PCI: 18.8% vs. CABG: 19.2%, p=0.94) was similar between the PCI and CABG groups but the MACE rate (PCI: 47.9% vs. CABG: 21.2%, p=0.006) was higher in the PCI group compared to the CABG group. In addition, the repeat revascularization rate was higher in the PCI group compared to the CABG group (PCI: 12.5% vs. CABG: 1.9%, p=0.046).
Conclusions
The CABG procedure was associated with a lower incidence of MACE and repeat revascularization for up to three years of follow-up in DN patients with CAD. However, the overall survival rate was similar in the CABG and PCI groups. Therefore, CABG may be superior to PCI with regard to MACE and repeat revascularization.
doi:10.3904/kjim.2007.22.3.139
PMCID: PMC2687692  PMID: 17939329
Diabetic Nephropathy; Coronary Artery Disease; Coronary Artery Bypass Grafting; Percutaneous Transluminal Coronary Angioplasty
10.  Effectiveness of Percutaneous Coronary Intervention With Drug‐Eluting Stents Compared With Bypass Surgery in Diabetics With Multivessel Coronary Disease: Comprehensive Systematic Review and Meta‐analysis of Randomized Clinical Data 
Background
Controversy persists regarding the optimal revascularization strategy for diabetic patients with multivessel coronary artery disease (MVD). Coronary artery bypass grafting (CABG) has been compared with percutaneous coronary intervention (PCI) using drug‐eluting stents (DES) in recent randomized controlled trials (RCTs).
Methods and Results
RCTs comparing PCI with DES versus CABG in diabetic patients with MVD who met inclusion criteria were analyzed (protocol registration No. CRD42013003693). Primary end point (major adverse cardiac events) was a composite of death, myocardial infarction, and stroke at a mean follow‐up of 4 years. Analyses were performed for each outcome by using risk ratio (RR) by fixed‐ and random‐effects models. Four RCTS with 3052 patients met inclusion criteria (1539 PCI versus 1513 CABG). Incidence of major adverse cardiac events was 22.5% for PCI and 16.8% for CABG (RR 1.34, 95% CI 1.16 to 1.54, P<0.0001). Similar results were obtained for death (14% versus 9.7%, RR 1.51, 95% CI 1.09 to 2.10, P=0.01), and MI (10.3% versus 5.9%, RR 1.44, 95% CI 0.79 to 2.6, P=0.23). Stroke risk was significantly lower with DES (2.3% versus 3.8%, RR 0.59, 95% CI 0.39 to 0.90, P=0.01) and subsequent revascularization was several‐fold higher (17.4% versus 8.0%, RR 1.85, 95% CI 1.0 to 3.40, P=0.05).
Conclusions
These data demonstrate that CABG in diabetic patients with MVD at low to intermediate surgical risk (defined as EUROSCORE <5) is superior to MVD PCI with DES. CABG decreased overall death, nonfatal myocardial infarction, and repeat revascularization at the expense of an increase in stroke risk.
doi:10.1161/JAHA.113.000354
PMCID: PMC3828792  PMID: 23926119
CABG; diabetes; multivessel disease; PCI
11.  Diagnostic Accuracy of Post Procedural Creatine Kinase, MB Form can Predict Long-Term Outcomes in Patients Undergoing Selective Percutaneous Coronary Intervention? 
Background:
Measuring cardiac markers in blood has been the main strategy for the diagnosis of acute myocardial infarction for nearly 50 years. Creatine kinase-MB (CK-MB) has been demonstrated to be a highly specific marker.
Objectives:
The present study aimed to assess the role of CK-MB changes following percutaneous coronary intervention (PCI) to predict one year outcomes of this procedure.
Patients and Methods:
This cohort study was conducted on 138 patients diagnosed with coronary artery disease who underwent PCI. Sixty-nine patients who had a CK-MB elevation ≥ 3 times upper limit of normal (ULN) post procedurally were considered as group I and 69 patients without cardiac enzyme rise after PCI were considered as the control group (group II). The composite end point of major adverse cardiac events (MACE) during one year was assessed by telephone follow-up or presentation at clinical visiting, and compared between the two groups. The MACE was defined as the appearance of at least one of the following events: mortality, repeated revascularization procedures, myocardial infarction, or cerebrovascular events.
Results:
Although one year mortality in the group I was 4 (5.8%), about two times greater than the other group 2 (2.9%), the difference was not significantly discrepant (P = 0.57). Moreover, 8 (11.6%) of patients in group I experienced one year MACE, while this rate in the other group was 4 (5.8%), with insignificant difference (P = 0.22). In group I, one case experienced coronary artery bypass surgery, one, exhibited cerebrovascular disease and one reported ST segment elevation myocardial infarction (STEMI), while two patients in the other group were suspicious of having non-ST segment elevation myocardial infarction (NSTEMI) and candidates for repeated PCI. Multivariate analysis revealed that increased post-procedural CK-MB ≥ 3 times UNL could not predict long-term MACE in patients who underwent selective PCI. Area under the curve (AUC) for predicting one year MACE was 0.593 (95% CI: 0.397 - 0.788), indicating inappropriate accuracy for this biomarker (P = 0.290).
Conclusions:
It seems that CK-MB ≥ 3 times ULN within 24 hours after PCI cannot independently predict one year MACE in patients undergoing PCI.
doi:10.5812/cardiovascmed.11738
PMCID: PMC4253746  PMID: 25478525
Creatine Kinase, MB Form; Angioplasty, Balloon, Coronary; Myocardial Infarction
12.  Revascularization for coronary artery disease in diabetes mellitus: Angioplasty, stents and coronary artery bypass grafting 
Patients with diabetes mellitus (DM) are prone to a diffuse and rapidly progressive form of atherosclerosis, which increases their likelihood of requiring revascularization. However, the unique pathophysiology of atherosclerosis in patients with DM modifies the response to arterial injury, with profound clinical consequences for patients undergoing percutaneous coronary intervention (PCI). Multiple studies have shown that DM is a strong risk factor for restenosis following successful balloon angioplasty or coronary stenting, with greater need for repeat revascularization and inferior clinical outcomes. Early data suggest that drug eluting stents reduce restenosis rates and the need for repeat revascularization irrespective of the diabetic state and with no significant reduction in hard clinical endpoints such as myocardial infarction and mortality. For many patients with 1- or 2-vessel coronary artery disease, there is little prognostic benefit from any intervention over optimal medical therapy. PCI with drug-eluting or bare metal stents is appropriate for patients who remain symptomatic with medical therapy. However, selection of the optimal myocardial revascularization strategy for patients with DM and multivessel coronary artery disease is crucial. Randomized trials comparing multivessel PCI with balloon angioplasty or bare metal stents to coronary artery bypass grafting (CABG) consistently demonstrated the superiority of CABG in patients with treated DM. In the setting of diabetes CABG had greater survival, fewer recurrent infarctions or need for re-intervention. Limited data suggests that CABG is superior to multivessel PCI even when drug-eluting stents are used. Several ongoing randomized trials are evaluating the long-term comparative efficacy of PCI with drug-eluting stents and CABG in patients with DM. Only further study will continue to unravel the mechanisms at play and optimal therapy in the face of the profoundly virulent atherosclerotic potential that accompanies diabetes mellitus.
doi:10.1007/s11154-010-9135-3
PMCID: PMC3076727  PMID: 20221852
Coronary artery bypass graft; Diabetes mellitus; Percutaneous coronary intervention; Revascularization; Stents
13.  On-pump beating heart coronary surgery for high risk patients requiring emergency multiple coronary artery bypass grafting 
Background
Cardiopulmonary bypass (CPB) with aortic cross-clamping and cardioplegic arrest remains the method of choice for patients requiring standard myocardial revascularization. Therefore, very high-risk patients presenting with acute coronary syndrome, unstable angina, onset of cardiac decompensation and requiring emergency multiple myocardial revascularization, can have a poor outcome. The on-pump beating heart technique can reduce the mortality and the morbidity in such a selected group of patients and this report describes our clinical experience.
Methods
Out of 290 patients operated for CABG from January 2005 to January 2006, 25 (8.6%) selected high-risk patients suffering from life threatening coronary syndrome (mean age 69 ± 7 years) and requiring emergency multiple myocardial revascularization, underwent on-pump beating heart surgery. The mean pre-operative left ventricle ejection fraction (LVEF) was 27 ± 8%. The majority of them (88%) suffered of tri-vessel coronary disease and 6 (24%) had a left main stump disease. Nine patients (35%) were on severe cardiac failure and seven among them (28%) received a pre-operative intra-aortic balloon pump. The pre-operative EuroScore rate was equal or above 8 in 18 patients (73%).
Results
All patients underwent on-pump-beating heart coronary revascularization. The mean number of graft/patient was 2.9 ± 0.6 and the internal mammary artery was used in 23 patients (92%). The mean CPB time was 84 ± 19 minutes. Two patients died during the recovery stay in the intensive care unit, and there were no postoperative myocardial infarctions between the survivors. Eight patients suffered of transitorily renal failure and 1 patient developed a sternal wound infection. The mean hospital stay was 12 ± 7 days. The follow-up was complete for all 23 patients survived at surgery and the mean follow-up time was 14 ± 5 months. One patient died during the follow-up for cardiac arrest and 2 patients required an implantable cardiac defibrillator. One year after surgery they all had a standard trans-thoracic echocardiogram showing a mean LVEF rate of 36 ± 11.8%.
Conclusion
Standard on-pump arrested heart coronary surgery has higher mortality and morbidity in emergencies. The on-pump beating heart myocardial revascularization seems to be a valid alternative for the restricted and selected cohort of patients suffering from life threatening coronary syndrome and requiring multiple emergency CABG.
doi:10.1186/1749-8090-3-38
PMCID: PMC2474599  PMID: 18597673
14.  Cost-effectiveness of percutaneous coronary intervention with drug-eluting stents in patients with multivessel coronary artery disease compared to coronary artery bypass surgery five-years after intervention 
Objectives
Cost-effectiveness of percutaneous coronary intervention (PCI) using drug-eluting stents (DES), and coronary artery bypass surgery (CABG) was analyzed in patients with multivessel coronary artery disease over a 5-year follow-up.
Background
DES implantation reducing revascularization rate and associated costs might be attractive for health economics as compared to CABG.
Methods
Consecutive patients with multivessel DES-PCI (n = 114, 3.3 ± 1.2 DES/patient) or CABG (n = 85, 2.7 ± 0.9 grafts/patient) were included prospectively. Primary endpoint was cost-benefit of multivessel DES-PCI over CABG, and the incremental cost-effectiveness ratio (ICER) was calculated. Secondary endpoint was the incidence of major adverse cardiac and cerebrovascular events (MACCE), including acute myocardial infarction (AMI), all-cause death, revascularization, and stroke.
Results
Despite multiple uses for DES, in-hospital costs were significantly less for PCI than CABG, with 4551 €/patient difference between the groups. At 5-years, the overall costs remained higher for CABG patients (mean difference 5400 € between groups). Cost-effectiveness planes including all patients or subgroups of elderly patients, diabetic patients, or Syntax score >32 indicated that CABG is a more effective, more costly treatment mode for multivessel disease. At the 5-year follow-up, a higher incidence of MACCE (37.7% vs. 25.8%; log rank P = 0.048) and a trend towards more AMI/death/stroke (25.4% vs. 21.2%, log rank P = 0.359) was observed in PCI as compared to CABG. ICER indicated 45615 € or 126683 € to prevent one MACCE or AMI/death/stroke if CABG is performed.
Conclusions
Cost-effectiveness analysis of DES-PCI vs. CABG demonstrated that CABG is the most effective, but most costly, treatment for preventing MACCE in patients with multivessel disease. © 2014 Wiley Periodicals, Inc.
doi:10.1002/ccd.25397
PMCID: PMC4262069  PMID: 24403120
coronary artery bypass surgery; percutaneous coronary intervention; drug-eluting stent; cost-benefit; follow-up study
15.  Magnetic Resonance Imaging (MRI) for the Assessment of Myocardial Viability 
Executive Summary
In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability, an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients undergoing viability assessment. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of noninvasive cardiac imaging modalities.
After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies that can be used for the assessment of myocardial viability: positron emission tomography, cardiac magnetic resonance imaging, dobutamine echocardiography, and dobutamine echocardiography with contrast, and single photon emission computed tomography.
A 2005 review conducted by MAS determined that positron emission tomography was more sensitivity than dobutamine echocardiography and single photon emission tomography and dominated the other imaging modalities from a cost-effective standpoint. However, there was inadequate evidence to compare positron emission tomography and cardiac magnetic resonance imaging. Thus, this report focuses on this comparison only. For both technologies, an economic analysis was also completed.
A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website).
The Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html
Positron Emission Tomography for the Assessment of Myocardial Viability: An Evidence-Based Analysis
Magnetic Resonance Imaging for the Assessment of Myocardial Viability: An Evidence-Based Analysis
Objective
The objective of this analysis is to assess the effectiveness and cost-effectiveness of cardiovascular magnetic resonance imaging (cardiac MRI) for the assessment of myocardial viability. To evaluate the effectiveness of cardiac MRI viability imaging, the following outcomes were examined: the diagnostic accuracy in predicting functional recovery and the impact of cardiac MRI viability imaging on prognosis (mortality and other patient outcomes).
Clinical Need: Condition and Target Population
Left Ventricular Systolic Dysfunction and Heart Failure
Heart failure is a complex syndrome characterized by the heart’s inability to maintain adequate blood circulation through the body leading to multiorgan abnormalities and, eventually, death. Patients with heart failure experience poor functional capacity, decreased quality of life, and increased risk of morbidity and mortality.
In 2005, more than 71,000 Canadians died from cardiovascular disease, of which, 54% were due to ischemic heart disease. Left ventricular (LV) systolic dysfunction due to coronary artery disease (CAD) 1 is the primary cause of heart failure accounting for more than 70% of cases. The prevalence of heart failure was estimated at one percent of the Canadian population in 1989. Since then, the increase in the older population has undoubtedly resulted in a substantial increase in cases. Heart failure is associated with a poor prognosis: one-year mortality rates were 32.9% and 31.1% for men and women, respectively in Ontario between 1996 and 1997.
Treatment Options
In general, there are three options for the treatment of heart failure: medical treatment, heart transplantation, and revascularization for those with CAD as the underlying cause. Concerning medical treatment, despite recent advances, mortality remains high among treated patients, while, heart transplantation is affected by the limited availability of donor hearts and consequently has long waiting lists. The third option, revascularization, is used to restore the flow of blood to the heart via coronary artery bypass grafting (CABG) or, in some cases, through minimally invasive percutaneous coronary interventions (balloon angioplasty and stenting). Both methods, however, are associated with important perioperative risks including mortality, so it is essential to properly select patients for this procedure.
Myocardial Viability
Left ventricular dysfunction may be permanent, due to the formation of myocardial scar, or it may be reversible after revascularization. Reversible LV dysfunction occurs when the myocardium is viable but dysfunctional (reduced contractility). Since only patients with dysfunctional but viable myocardium benefit from revascularization, the identification and quantification of the extent of myocardial viability is an important part of the work-up of patients with heart failure when determining the most appropriate treatment path. Various non-invasive cardiac imaging modalities can be used to assess patients in whom determination of viability is an important clinical issue, specifically:
dobutamine echocardiography (echo),
stress echo with contrast,
SPECT using either technetium or thallium,
cardiac magnetic resonance imaging (cardiac MRI), and
positron emission tomography (PET).
Dobutamine Echocardiography
Stress echocardiography can be used to detect viable myocardium. During the infusion of low dose dobutamine (5 – 10 µg/kg/min), an improvement of contractility in hypokinetic and akentic segments is indicative of the presence of viable myocardium. Alternatively, a low-high dose dobutamine protocol can be used in which a biphasic response characterized by improved contractile function during the low-dose infusion followed by a deterioration in contractility due to stress induced ischemia during the high dose dobutamine infusion (dobutamine dose up to 40 ug/kg/min) represents viable tissue. Newer techniques including echocardiography using contrast agents, harmonic imaging, and power doppler imaging may help to improve the diagnostic accuracy of echocardiographic assessment of myocardial viability.
Stress Echocardiography with Contrast
Intravenous contrast agents, which are high molecular weight inert gas microbubbles that act like red blood cells in the vascular space, can be used during echocardiography to assess myocardial viability. These agents allow for the assessment of myocardial blood flow (perfusion) and contractile function (as described above), as well as the simultaneous assessment of perfusion to make it possible to distinguish between stunned and hibernating myocardium.
SPECT
SPECT can be performed using thallium-201 (Tl-201), a potassium analogue, or technetium-99 m labelled tracers. When Tl-201 is injected intravenously into a patient, it is taken up by the myocardial cells through regional perfusion, and Tl-201 is retained in the cell due to sodium/potassium ATPase pumps in the myocyte membrane. The stress-redistribution-reinjection protocol involves three sets of images. The first two image sets (taken immediately after stress and then three to four hours after stress) identify perfusion defects that may represent scar tissue or viable tissue that is severely hypoperfused. The third set of images is taken a few minutes after the re-injection of Tl-201 and after the second set of images is completed. These re-injection images identify viable tissue if the defects exhibit significant fill-in (> 10% increase in tracer uptake) on the re-injection images.
The other common Tl-201 viability imaging protocol, rest-redistribution, involves SPECT imaging performed at rest five minutes after Tl-201 is injected and again three to four hours later. Viable tissue is identified if the delayed images exhibit significant fill-in of defects identified in the initial scans (> 10% increase in uptake) or if defects are fixed but the tracer activity is greater than 50%.
There are two technetium-99 m tracers: sestamibi (MIBI) and tetrofosmin. The uptake and retention of these tracers is dependent on regional perfusion and the integrity of cellular membranes. Viability is assessed using one set of images at rest and is defined by segments with tracer activity greater than 50%.
Cardiac Positron Emission Tomography
Positron emission tomography (PET) is a nuclear medicine technique used to image tissues based on the distinct ways in which normal and abnormal tissues metabolize positron-emitting radionuclides. Radionuclides are radioactive analogs of common physiological substrates such as sugars, amino acids, and free fatty acids that are used by the body. The only licensed radionuclide used in PET imaging for viability assessment is F-18 fluorodeoxyglucose (FDG).
During a PET scan, the radionuclides are injected into the body and as they decay, they emit positively charged particles (positrons) that travel several millimetres into tissue and collide with orbiting electrons. This collision results in annihilation where the combined mass of the positron and electron is converted into energy in the form of two 511 keV gamma rays, which are then emitted in opposite directions (180 degrees) and captured by an external array of detector elements in the PET gantry. Computer software is then used to convert the radiation emission into images. The system is set up so that it only detects coincident gamma rays that arrive at the detectors within a predefined temporal window, while single photons arriving without a pair or outside the temporal window do not active the detector. This allows for increased spatial and contrast resolution.
Cardiac Magnetic Resonance Imaging
Cardiac magnetic resonance imaging (cardiac MRI) is a non-invasive, x-ray free technique that uses a powerful magnetic field, radio frequency pulses, and a computer to produce detailed images of the structure and function of the heart. Two types of cardiac MRI are used to assess myocardial viability: dobutamine stress magnetic resonance imaging (DSMR) and delayed contrast-enhanced cardiac MRI (DE-MRI). DE-MRI, the most commonly used technique in Ontario, uses gadolinium-based contrast agents to define the transmural extent of scar, which can be visualized based on the intensity of the image. Hyper-enhanced regions correspond to irreversibly damaged myocardium. As the extent of hyper-enhancement increases, the amount of scar increases, so there is a lower the likelihood of functional recovery.
Evidence-Based Analysis
Research Questions
What is the diagnostic accuracy of cardiac MRI for detecting myocardial viability?
What is the impact of cardiac MRI viability imaging on prognosis (mortality and other clinical outcomes)?
How does cardiac MRI compare with cardiac PET imaging for the assessment of myocardial viability?
What is the contribution of cardiac MRI viability imaging to treatment decision making?
Is cardiac MRI cost-effective compared with other cardiac imaging modalities for the assessment of myocardial viability?
Literature Search
A literature search was performed on October 9, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2005 until October 9, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria full-text articles were obtained. In addition, published systematic reviews and health technology assessments were reviewed for relevant studies published before 2005. Reference lists were also examined for any additional relevant studies not identified through the search. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology.
Inclusion Criteria
English language full-reports
Published between January 1, 2005 and October 9, 2009
Health technology assessments, systematic reviews, meta-analyses, randomized controlled trials (RCTs), and observational studies
Patients with chronic, known coronary artery disease (CAD)
Used contrast-enhanced MRI
Assessment of functional recovery ≥ 3 months after revascularization
Exclusion Criteria
< 20 patients
< 18 years of age
Patients with non-ischemic heart disease
Studies conducted exclusively in patients with acute myocardial infarction (MI)
Studies where TP, TN, FP, FN cannot be determined
Outcomes of Interest
Sensitivity
Specificity
Positive predictive value (PPV)
Negative Predictive value (NPV)
Positive likelihood ratio
Negative likelihood ratio
Diagnostic accuracy
Mortality rate (for prognostic studies)
Adverse events
Summary of Findings
Based on the available very low quality evidence, MRI is a useful imaging modality for the detection of viable myocardium. The pooled estimates of sensitivity and specificity for the prediction of regional functional recovery as a surrogate for viable myocardium are 84.5% (95% CI: 77.5% – 91.6%) and 71.0% (95% CI: 68.8% – 79.2%), respectively.
Subgroup analysis demonstrated a statistically significant difference in the sensitivity of MRI to assess myocardial viability for studies using ≤25% hyperenhancement as a viability threshold versus studies using ≤50% hyperenhancement as their viability threshold [78.7 (95% CI: 69.1% - 88.2%) and 96.2 (95% CI: 91.8 – 100.6); p=0.0044 respectively]. Marked differences in specificity were observed [73.6 (95% CI: 62.6% - 84.6%) and 47.2 (95% CI: 22.2 – 72.3); p=0.2384 respectively]; however, these findings were not statistically significant.
There were no statistically significant differences between the sensitivities or specificities for any other subgroups including mean preoperative LVEF, imaging method for function recovery assessment, and length of follow-up.
There was no evidence available to determine whether patients with viable myocardium who are revascularized have a lower mortality rate than those who are treated with medical therapy.
PMCID: PMC3426228  PMID: 23074392
16.  Smoking status and survival: impact on mortality of continuing to smoke one year after the angiographic diagnosis of coronary artery disease, a prospective cohort study 
Background
Smoking is an undertreated risk factor for coronary artery disease (CAD) and is associated with adverse outcomes after myocardial infarction. Aims of our study were to determine if management of CAD by medical therapy (MT) alone or with coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) influence smoking status at one year following angiography and if a change in smoking status at one year influences long term survival.
Methods
Prospective cohort study using the APPROACH registry. Two cohorts were examined: (1) 11,334 patients who returned a one year follow-up questionnaire; (2) 4,246 patients propensity-matched based on their post-angiography treatment - MT or revascularization (RV). Multivariate modeling and survival analysis were used.
Results
In the propensity-matched cohort, quit rates at one year were greater among CABG patients (68%) than PCI (37%) or MT patients (47%). Smokers in the RV group, who self-reported quitting at one year, had a significantly reduced mortality compared to those who continued to smoke.
Conclusions
CABG patients were more likely to quit smoking than those treated with MT alone or PCI. Quitting smoking was associated with improved long-term survival; smoking remains a key risk factor for mortality in patients with CAD. These data underscore the importance of nicotine addiction management in patients with CAD and the need to emphasize cessation particularly in those patients undergoing MT or PCI.
doi:10.1186/1471-2261-14-133
PMCID: PMC4190449  PMID: 25274407
Smoking cessation; Coronary artery disease; Coronary artery bypass grafting; Percutaneous coronary intervention
17.  Troponin-I release after cardiac surgery with different surgical techniques and post-operative neurological outcomes 
Cerebral hypoperfusion during cardiopulmonary bypass surgery has been thought to be a factor in the aetiology of brain damage with evidence of post-operative neurological deficits. Cardiac-specific biomarkers such as troponin-I, troponin-T and CK-MB have been used extensively to predict myocardial injury and ischaemia. This prospective study investigateed the level of troponin-I release in both off-pump and CPB-technique CABG surgery, as well as postulated a relationship of troponin release and post-operative neurological outcome. A total of 44 adult patients undergoing coronary artery bypass graft (CABG) were enrolled into either an off-pump or on-pump groups, with 22 patients participating in each. Group A (on-pump) underwent myocardial revascularisation with CPB and cardioplegic arrest, while Group B (off pump) underwent beating heart surgery. The measurement of troponin-I is a 1-step enzyme immunoassay method, with specificity and sensitivity set at 0.4 ug/mL. Neurological assessment was done using the NIH Stroke Scale, and neuropsychologic assessment was assessed on cognitive function using modified Weschler Memory Scale, for which scores were standardized to achieve a composite measure of concentration. A set of statistical analysis was done to correlate troponin-I release with different surgical techniques of CPB and OPCAB. Although each independent technique showed a marked rise of troponin-I from baseline to 6 hours post-operatively, the difference in troponin release was not significant between the 2 groups at specified time intervals (p=0.124). There was however a significant correlation of troponin-I release with the number of grafts used in the surgery, irrespective of the type of grafts or surgical technique. None of the patients in either group showed any neurological or cognitive deficits presenting at day 3 and day 7 post-operatively. The findings of this study demonstrate that there is no significant short-term cognitive or neurological dysfunctions post-operatively, as indicated by troponin-I release in assessing the severity of myocardial injury.
PMCID: PMC2323524  PMID: 18523619
18.  Beneficial effects of statins after percutaneous coronary intervention 
Background
Evidence about the efficacy of statin treatment among patients after percutaneous coronary intervention (PCI) is very limited. The rapid advancement in PCI technology and near universal use of adjunctive cardioprotective medications make it necessary to formally assess the effect of statin therapy on cardiac events after PCI.
Design
This was a multicenter prospective cohort study
Methods
Patients who received stent implantation and survived to hospital discharge from the National Heart, Lung, and Blood Institute Dynamic Registry from 2004 to 2006 formed the study cohort. Patients with cardiogenic shock, in-hospital adverse events [including myocardial infarction and coronary artery bypass graft surgery (CABG)], liver disease, renal disease, alcoholism, or drug abuse were excluded. The occurrences of death, CABG, and repeat PCI, and repeat revascularization were collected over 1-year follow-up.
Results
Of the 3227 patients evaluated, 2737 (85%) were prescribed a statin at discharge. By 1-year follow-up, incident events were 98 deaths, 44 CABG, 290 repeat PCI procedures, and 328 repeat revascularizations. After propensity score adjustment, postdischarge statin therapy was associated with lower risks of death [hazard ratio (HR)λ=λ0.58, 95% confidence interval (CI): 0.36–0.93, Pλ=λ0.02], CABG (HRλ=λ0.49, 95% CI: 0.24–1.00, Pλ=λ0.05), and repeat revascularization (HRλ=λ0.74, 95% CI: 0.56–1.00, Pλ=λ0.05).
Conclusion
These results support the routine use of statin therapy after PCI.
doi:10.1097/HJR.0b013e32832a4e3b
PMCID: PMC3219755  PMID: 19369875
mortality; propensity score; repeat revascularization; stent
19.  Changing outcomes of coronary revascularization in British Columbia, 1995–2001 
The Canadian Journal of Cardiology  2006;22(14):1197-1203.
OBJECTIVES
To examine outcomes following all first coronary revascularization procedures, isolated coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI) on British Columbia (BC) resident adults from 1995 to 2001.
METHODS
CABG and PCI data were obtained from the BC Cardiac Registry, and mortality data were obtained from the BC Vital Statistics Agency. Analysis was performed by annual cohorts, and the rates reported are unadjusted.
RESULTS
An increasing percentage of revascularization procedures was performed with PCI (62% in 1995 to 73% in 2001; P<0.001) due to the increased use of PCI procedures. Except in emergent cases, 30-day mortality improved after PCI (1.8% to 1.1%; P=0.02) and CABG (1.8% to 1.2%; P=0.01). Emergent cases accounted for 9.0% of PCIs and 2.7% of CABGs, the percentage treated by CABG decreasing from 14.5% in 1995 to 7.5% by 2001 (P<0.001). Mortality rates among emergent cases was higher at 30 days, with no trend in PCI mortality (12%) but a substantial reduction in 30-day mortality after CABG (28% to 10%; P=0.003). One-year survival free from repeat revascularization following PCI increased from 73% in 1995 to 83% in 2001 (P<0.001) and from 94% to 95% (P<0.005) following CABG.
CONCLUSIONS
Improvements in procedure-related mortality observed in trials have extended to clinical practice. With respect to emergent cases, an increasing proportion were treated by PCI with no change in PCI mortality but associated with a drop in surgical mortality. There has been a consistent and substantial drop in the need for repeat procedures within one year for patients selected for PCI.
PMCID: PMC2569081  PMID: 17151768
Angiography; Angioplasty; Epidemiology; Surgery
20.  Racial Disparities in the Use of Cardiac Revascularization: Does Local Hospital Capacity Matter? 
PLoS ONE  2013;8(7):e69855.
Objective
To assess the extent to which the observed racial disparities in cardiac revascularization use can be explained by the variation across counties where patients live, and how the within-county racial disparities is associated with the local hospital capacity.
Data Sources
Administrative data from Pennsylvania Health Care Cost Containment Council (PHC4) between 1995 and 2006.
Study Design
The study sample included 207,570 Medicare patients admitted to hospital for acute myocardial infarction (AMI). We identified the use of coronary artery bypass graft (CABG) and percutaneous coronary intervention (PCI) procedures within three months after the patient’s initial admission for AMI. Multi-level hierarchical models were used to determine the extent to which racial disparities in procedure use were attributable to the variation in local hospital capacity.
Principal Findings
Blacks were less likely than whites to receive CABG (9.1% vs. 5.8%; p<0.001) and PCI (15.7% vs. 14.2%; p<0.001). The state-level racial disparity in use rate decreases for CABG, and increases for PCI, with the county adjustment. Higher number of revascularization hospitals per 1,000 AMI patients was associated with smaller within-county racial differences in CABG and PCI rates. Meanwhile, very low capacity of catheterization suites and AMI hospitals contributed to significantly wider racial gap in PCI rate.
Conclusions
County variation in cardiac revascularization use rates helps explain the observed racial disparities. While smaller hospital capacity is associated with lower procedure rates for both racial groups, the impact is found to be larger on blacks. Therefore, consequences of fewer medical resources may be particularly pronounced for blacks, compared with whites.
doi:10.1371/journal.pone.0069855
PMCID: PMC3713060  PMID: 23875005
21.  Outcomes following percutaneous coronary intervention and coronary artery bypass grafting surgery in Chinese, South Asian and white patients with acute myocardial infarction: administrative data analysis 
Background
Little is known on whether there are ethnic differences in outcomes following percutaneous coronary intervention (PCI) and coronary artery bypass grafting surgery (CABG) after acute myocardial infarction (AMI). We compared 30-day and long-term mortality, recurrent AMI, and congestive heart failure in South Asian, Chinese and White patients with AMI who underwent PCI and CABG.
Methods
Hospital administrative data in British Columbia (BC), Canada were linked to the BC Cardiac Registry to identify all patients with AMI who underwent PCI (n = 4729) or CABG (n = 1687) (1999–2003). Ethnicity was determined from validated surname algorithms. Logistic regression for 30-day mortality and Cox proportional-hazards models were adjusted for age, sex, socio-economic status, severity of coronary disease, comorbid conditions, time from AMI to a revascularization procedure and distance to the nearest hospital.
Results
Following PCI, Chinese had higher short-term mortality (Odds Ratio (OR): 2.36, 95% CI: 1.12-5.00; p = 0.02), and South Asians had a higher risk for recurrent AMI (OR: 1.34, 95% CI: 1.08-1.67, p = 0.007) and heart failure (OR 1.81, 95% CI: 1.00-3.29, p = 0.05) compared to White patients. Risk of heart failure was higher in South Asian patients who underwent CABG compared to White patients (OR (95% CI) = 2.06 (0.92-4.61), p = 0.08). There were no significant differences in mortality following CABG between groups.
Conclusions
Chinese and South Asian patients with AMI and PCI or CABG had worse outcomes compared to their White counterparts. Further studies are needed to confirm these findings and investigate potential underlying causes.
doi:10.1186/1471-2261-13-121
PMCID: PMC3890497  PMID: 24369071
PCI; CABG; Ethnicity; AMI; Outcomes
22.  Stress Imaging Utilization and Repeat Revascularization among Medicare Patients with High Risk Coronary Artery Disease 
The American journal of cardiology  2012;110(9):1270-1274.
The optimal use of stress testing after coronary revascularization remains unclear, and over-utilization of stress testing may increase rates of repeat revascularization. We analyzed the relationship at both the patient and regional level between the use of stress testing and repeat revascularization for a cohort of Medicare beneficiaries receiving revascularization within 30 days of an admission for symptomatic coronary artery disease (CAD).The sample consisted of 219,748 Medicare beneficiaries older than 65 years who received percutaneous coronary intervention (PCI) or cardiac bypass surgery (CABG) following hospital admission for symptomatic CAD in 2003–2004. Medicare claims data through 2008 identified the use of stress testing and repeat revascularization. Associations between the cumulative incidence of stress testing and repeat revascularization were analyzed using linear regressions. Within six years of initial revascularization, the cumulative incidence of events was 0.61 for stress testing and 0.23 for repeat revascularization. Most (53.1%) repeat revascularizations were preceded by a stress test. Only 10.3% of repeat revascularization procedures were preceded by myocardial infarction. Four-year cumulative incidence of repeat revascularization and stress testing varied between the Hospital Referral Regions represented by the sample, and the positive correlation between the rates by HRR accounted for only a small portion of the total HRR variation in revascularization rates. Stress testing is commonly performed among Medicare patients after initial revascularization, and the majority of repeat procedures are performed for stable CAD. Variation in stress testing patterns only explains a modest fraction of regional variation in repeat revascularization rates.
doi:10.1016/j.amjcard.2012.06.029
PMCID: PMC3622200  PMID: 22819426
Stress testing; Coronary revascularization; Medicare claims data
23.  Narrowing Gender Differences in Procedure Use for Acute Myocardial Infarction 
OBJECTIVE
To examine age-specific gender differences and trends over time in the management of patients with acute myocardial infarction (AMI).
DESIGN
Cross-sectional study of patients admitted with AMI from a community-wide perspective over a 10-year period (1990–1999).
SETTING
All hospitals in the Worcester (Mass) metropolitan area (1990 census = 437,000).
PATIENTS/PARTICIPANTS
We identified 2,037 women and 2,645 men who were hospitalized in the Worcester metropolitan area with confirmed AMI during six 1-year periods between 1990 and 1999. Four age groups (<55, 55 to 64, 65 to 74 and ≥75 years) of men and women were studied.
MEASUREMENTS AND MAIN RESULTS
Use of echocardiography, exercise treadmill testing (ETT), cardiac catheterization, percutaneous coronary interventions (PCI), and coronary artery bypass grafting (CABG) during the index hospitalization was examined in relation to age and gender. Overall, women were less likely to undergo ETT, cardiac catheterization, and CABG than were men, and these trends remained after controlling for potentially confounding factors. Between 1990 and 1999, there was a dramatic decrease in ETT, whereas the use of echocardiography remained unchanged. There were marked increases over time in the use of cardiac catheterization and PCI in women and men. Use of cardiac catheterization and PCI increased to a greater extent in women as compared to men. In patients who underwent cardiac catheterization, rates of coronary revascularization were similar between men and women.
CONCLUSIONS
Our data suggest that women and men with AMI are treated differently with respect to use of diagnostic and revascularization procedures. However, gender differences in the use of these diagnostic and interventional approaches have narrowed over time.
doi:10.1046/j.1525-1497.2003.20929.x
PMCID: PMC1494881  PMID: 12823649
myocardial infarction; gender differences; procedures
24.  A Cross-sectional study of stand-alone Percutaneous Coronary Intervention in a Nigerian Cardiac Catheterization Laboratory 
Background
There is a paucity of diagnostic and therapeutic facilities in Nigeria to confirm coronary artery disease and offer appropriate interventional therapy. There is now a private cardiac catheterization laboratory in Lagos but as there are no sustained Open Heart Surgery programmes, percutaneous coronary interventions are currently being performed without surgical backup. This study was designed to assess results of stand-alone percutaneous coronary intervention (PCI) as currently practiced in Lagos, Nigeria.
Methods
This cross-sectional study was conducted between July 2009 and July 2012. The study included all patients that underwent PCI in Lagos. Data was extracted from a prospectively maintained database.
Results
Coronary artery disease was confirmed in 80 (52.6%) of 152 Nigerians referred with a diagnosis of Ischaemic Heart Disease. There were 53 males (66.2%) and 27 females (33.8%). The average age was 60.3 +/−9.6 years and average euroscore was 4.5 +/−3.1. Of the 80 patients, 77 (96.3%) had significant stenoses and were candidates for revascularization. Distribution of significant stenoses was one in 32 patients (41.5%), two in 11 patients (14.3%), three in 19 patients (24.7%), four in 13 patients (16.9%) and five in 2 patients (2.6%). PCI was performed in 48 (62.3%) of the patients eligible for revascularization as the coronary anatomy in the remaining patients was not suitable for PCI. The indication for PCI was for myocardial infarction or unstable angina in 39 patients (81.2%). PCI was performed with PTCA plus stenting in 41 patients (85.4%) and with PTCA alone in 7 patients (14.6%) with good angiographic results. Overall 29 of the 48 patients (60.4%) had complete revascularization of significant stenoses. Complications of PCI were bleeding that required blood transfusion in 1 patient (2.1%), minor femoral haematomas in 2 patients (4.2%), and a major adverse clinical event in 1 patient (2.1%).
Conclusion
A stand-alone PCI programme has been developed in Lagos, Nigeria. Both elective and urgent PCIs have been performed with no mortalities and a low complication rate. Increased volumes will however accrue and complete revascularization rates would be improved with the establishment of Open Heart Surgery programmes to provide CABG as back-up for PCI and alternate therapy for more complex lesions.
doi:10.1186/1471-2261-14-8
PMCID: PMC3897932  PMID: 24433419
25.  Mode of Coronary Revascularization and Short term Clinical Outcomes in Patients with Chronic Kidney Disease 
Pakistan Journal of Medical Sciences  2014;30(6):1180-1185.
Background and Objective: Percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) surgery are two alternative methods for coronary revascularization, but it remains controversial as which one is associated with lower risks of worse clinical outcomes for chronic kidney disease (CKD) patients. We determined the mode of coronary revascularization (PCI vs. CABG) which is associated with lower risk of mortality and morbidity in CKD patients.
Methods: In this cross sectional study, 159 patients with CKD were enrolled from single center of coronary revascularization at Aga Khan University Hospital Karachi between January 2012 and August 2013. All patients with CKD underwent PCI or CABG. The primary outcome was in-hospital composite of death, myocardial infarction (MI), or stroke. We evaluated which mode of coronary revascularization was associated with reduced risks of clinical outcomes.
Results: Out of 159 patients with CKD, 85 (53.5%) received PCI and 74 (46.5%) received CABG. The primary finding of this study is that more patients with moderate to severe CKD underwent PCI and more patients with mild to moderate CKD underwent CABG. In both these categories, no difference was observed in clinical outcomes. There are few factors like age, ST- elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI) and number of coronary artery disease predicted PCI as treatment strategy in patients with moderate to severe CKD.
Conclusion: Patients with moderate to severe CKD have similar rates of short term clinical outcomes whether they underwent PCI or CABG. Therefore, PCI can be acceptable and less invasive treatment option alternative to CABG, particularly in patients with moderate to severe CKD.
doi:10.12669/pjms.306.5540
PMCID: PMC4320696
Chronic kidney disease; Creatinine clearance; Coronary revascularization; Percutaneous coronary intervention; Coronary artery bypass graft

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