All procedures have inherent risk. Our patient endured a sequence of rare life-threatening complications from commonly preformed procedures. The sequence of these complications was; large pericardial effusion post implantable cardioverter-defibrillator (ICD) implantation with echocardiographic signs of tamponade, left main narrowing post radiofrequency ablation, and late stent thrombosis post coronary intervention with a bare metal stent. All these occurred to one unfortunate young man. Furthermore, our patient demonstrated an unintended benefit of ICD which saved his life.
Implantable cardioverter-defibrillator; radiofrequency ablation; coronary injury; pericardial effusion
Elderly patients have more cardiovascular risk factors and a greater burden of ischemic disease than younger patients.
To examine the impact of age on clinical presentation and outcomes in patients presenting with acute coronary syndrome (ACS).
Methods and material
Collected data from the 2nd Gulf Registry of Acute Coronary Events (Gulf RACE-2), which is a prospective multicenter study from six adjacent Arab Middle Eastern Gulf countries. Patients were divided into 3 groups according to their age: ≤50 years, 51–70 years and >70 years and their clinical characteristics and outcomes were analyzed. Mortality was assessed at one and 12 months.
Statistical analysis used
One-way ANOVA test for continuous variables, Pearson chi-square (X2) test for categorical variables and multivariate logistic regression analysis for predictors were performed.
Among 7930 consecutive ACS patients; 2755 (35%) were ≤50 years, 4110 (52%) were 51–70 years and 1065 (13%) >70 years old. The proportion of women increased with increasing age (13% among patients ≤50 years to 31% among patients > 70 years). The risk factor pattern varied with age; younger patients were more often obese, smokers and had a positive family history of CAD, whereas older patients more likely to have diabetes mellitus, hypertension, and dyslipidemia. Advancing age was associated with under-treatment evidence-based therapies. Multivariate logistic regression analysis after adjusting for relevant covariates showed that old age was independent predictors for re-ischemia (OR 1.29; 95% CI 1.03–1.60), heart failure (OR 2.8; 95% CI 2.17–3.52) and major bleeding (OR 4.02; 95% CI 1.37–11.77) and in-hospital mortality (age 51–70: OR 2.67; 95% CI 1.86–3.85, and age >70: OR 4.71; 95% CI 3.11–7.14).
Despite being higher risk group, elderly are less likely to receive evidence-based therapies and had worse outcomes. Guidelines adherence is highly recommended in elderly.
Acute coronary syndrome; Age; Elderly
Ivabradine is a novel selective If current inhibitor with anti-ischemic and antianginal activity.
To assess the effect of the selective If current inhibitor ivabradine on heart rate, angina pectoris, and functional capacity in stable patients with chronic coronary artery disease on maximally tolerated medical therapy.
Materials and Methods:
Consecutive patients from the out-patient cardiology clinic with stable coronary artery disease documented by coronary angiography were included. Patients had to be on maximally tolerated medical therapy with β-blockers, angiotensin-converting enzyme inhibitors or receptor blockers (ACE-I or ARB), antiplatelets, statins, nitrates, and anti-metabolics with a baseline heart rate of at least 70 beats per minute. All patients underwent assessment of angina (Canadian Cardiovascular Society Angina Class: CCS I to IV) and functional capacity (using a validated self-administered questionnaire), at baseline and after 4 months of ivabradine therapy.
Twenty patients were enrolled (mean age 47 ± 7 years, all male, 60% with hypertension, 30% with diabetes mellitus). Patients were on optimal medical regimen of aspirin (100%), β-blocker (100%), statins (100%), clopidogrel (90%), nitrates (35%), anti-metabolics (90%), and ACE-I or ARB (95%). At baseline, the majority of patients (90%) were in CCS class II-IV. All patients were started on ivabradine 5 mg twice daily, and in 12 patients the dose was increased to 7.5 mg twice daily. After 4 months of treatment, the heart rate was significantly reduced from an average of 82 ± 8 to 68 ± 6 bpm (P < 0.001). The reduction in heart rate was accompanied by a significant improvement in functional capacity (score 3.5 ± 0.9 to 4.7 ± 0.7, P < 0.001) and angina classification; at baseline 10% of the patients were in CCS class I compared to 50% after 4 months of therapy (P = 0.01). No symptomatic bradycardia was reported with ivabradine.
The addition of ivabradine to optimal medical therapy in patients with stable coronary artery disease is associated with significant improvement in anginal symptoms and functional capacity.
Heart rate; ischemic heart disease; ivabradine
Gender-related differences in mortality of acute coronary syndrome (ACS) have been reported. The extent and causes of these differences in the Middle-East are poorly understood. We studied to what extent difference in outcome, specifically 1-year mortality are attributable to demographic, baseline clinical differences at presentation, and management differences between female and male patients.
Baseline characteristics, treatment patterns, and 1-year mortality of 7390 ACS patients in 65 hospitals in 6 Arabian Gulf countries were evaluated during 2008–2009, as part of the 2nd Gulf Registry of Acute Coronary Events (Gulf RACE-2). Women were older (61.3±11.8 vs. 55.6±12.4; P<0.001), more overweight (BMI: 28.1±6.6 vs. 26.7±5.1; P<0.001), and more likely to have a history of hypertension, hyperlipidemia or diabetes. Fewer women than men received angiotensin-converting enzyme inhibitors (ACE), aspirin, clopidogrel, beta blockers or statins at discharge. They also underwent fewer invasive procedures including angiography (27.0% vs. 34.0%; P<0.001), percutaneous coronary intervention (PCI) (10.5% vs. 15.6%; P<0.001) and reperfusion therapy (6.9% vs. 20.2%; P<0.001) than men. Women were at higher unadjusted risk for in-hospital death (6.8% vs. 4.0%, P<0.001) and heart failure (HF) (18% vs. 11.8%, P<0.001). Both 1-month and 1-year mortality rates were higher in women than men (11% vs. 7.4% and 17.3% vs. 11.4%, respectively, P<0.001). Both baseline and management differences contributed to a worse outcome in women. Together these variables explained almost all mortality disparities.
Differences between genders in mortality appeared to be largely explained by differences in prognostic variables and management patterns. However, the origin of the latter differences need further study.
Atrial fibrillation (AF) is a major global public health problem. Observational studies are necessary to understand patient characteristics, management, and outcomes of this common arrhythmia. Accordingly, our objective was to describe the current status of published prospective observational studies of AF.
Methods and results
MEDLINE and EMBASE (to June 2012) and reference lists of eligible studies were searched for English-language prospective observational registries of AF (n ⩾ 100 and follow-up ⩾6 months). Two reviewers independently extracted data. Disagreements were resolved by consensus. Eight prospective studies enrolled a total of 17,924 patients with AF (total 41,306 patient-years of exposure; follow-up 11 months to 9.9 years). The majority of subjects were enrolled in Europe (74%) or North America (21%), and 0.3% had rheumatic AF. The most consistently reported comorbidities were diabetes mellitus (range 5–18%), hypertension (39–68%), heart failure (5–58%), and prior stroke (4–17%). Three studies did not report all the variables necessary to calculate the currently recommended stroke risk assessment score, and no study reported all the variables required to calculate a recently validated bleeding risk score. The most consistently reported management features were oral anticoagulation (32–64%) and aspirin (28–61%) use. Calcium channel blockers were less frequently used than other rate controlling agents, and digoxin was most common in the single study from Africa (63%). Total mortality was reported in all studies, while data on stroke/systemic embolism, hospitalizations, and major hemorrhage rates were not always reported.
Current literature on real-world management of AF is relatively limited with inadequate data to allow detailed comparisons among reports. Data on rheumatic AF and from Africa and the developing world in general are sparse.
Atrial fibrillation; Systematic review
Stroke is a potential complication of acute coronary syndrome (ACS). The aim of this study was to identify the prevalence, risk factors predisposing to stroke, in-hospital and 1-year mortality among patients presenting with ACS in the Middle East.
For a period of 9 months in 2008 to 2009, 7,930 consecutive ACS patients were enrolled from 65 hospitals in 6 Middle East countries.
The prevalence of in-hospital stroke following ACS was 0.70%. Most cases were ST segment elevation MI-related (STEMI) and ischemic stroke in nature. Patients with in-hospital stroke were 5 years older than patients without stroke and were more likely to have hypertension (66% vs. 47.6%, P = 0.001). There were no differences between the two groups in regards to gender, other cardiovascular risk factors, or prior cardiovascular disease. Patients with stroke were more likely to present with atypical symptoms, advanced Killip class and less likely to be treated with evidence-based therapies. Independent predictors of stroke were hypertension, advanced killip class, ACS type –STEMI and cardiogenic shock. Stroke was associated with increased risk of in-hospital (39.3% vs. 4.3%) and one-year mortality (52% vs. 12.3%).
There is low incidence of in-hospital stroke in Middle-Eastern patients presenting with ACS but with very high in-hospital and one-year mortality rates. Stroke patients were less likely to be appropriately treated with evidence-based therapy. Future work should be focused on reducing the risk and improving the outcome of this devastating complication.
Acute coronary syndrome; Myocardial infarction; Stroke; Risk factors; Prognosis
We describe the baseline characteristics, management, and in-hospital outcomes of patients in the United Arab Emirates (UAE) with DM admitted with an acute coronary syndrome (ACS) and assess the influence of DM on in-hospital mortality. Data was analyzed from 1697 patients admitted to various hospitals in the UAE with a diagnosis of ACS in 2007 as part of the 1st Gulf RACE (Registry of Acute Coronary Events). Of 1697 patients enrolled, 668 (39.4%) were diabetics. Compared to patients without DM, diabetic patients were more likely to have a past history of coronary artery disease (49.1% versus 30.1%, P < 0.001), hypertension (67.2% versus 36%, P < 0.001), and prior revascularization (21% versus 11.4%, P < 0.001). They experienced more in-hospital recurrent ischemia (8.5% versus 5.1%; P = 0.004) and heart failure (20% versus 10%; P < 0.001). The mortality rate was 2.7% for diabetics and 1.6% for nondiabetics (P = 0.105). After age adjustment, in-hospital mortality increased by 3.5% per year of age (P = 0.016). This mortality was significantly higher in females than in males (P = 0.04). ACS patients with DM have different clinical characteristics and appear to have poorer outcomes.
Little is known about thrombolytic therapy patterns in patients with ST-elevation myocardial infarction (STEMI) in the Middle East. The objective of this study was to evaluate the clinical profile and mortality of STEMI patients who arrived in hospital within 12 hours from pain onset and received thrombolytic therapy.
Patients and Methods:
This was a prospective, multinational, multi-centre, observational survey of consecutive acute coronary syndrome patients admitted to 65 hospitals in six Middle Eastern countries during the period between October 2008 and June 2009, as part of Gulf RACE-II (Registry of Acute Coronary Events). Analyses were performed using univariate statistics.
Out of 2,465 STEMI patients, 66% (n = 1,586) were thrombolysed with namely: streptokinase (43%), reteplase (44%), tenecteplase (10%), and alteplase (3%). 22.7% received no reperfusion. Median age of the study cohort was 50 (45-59) years with majority being males (91%). The overall median symptom onset-to-presentation and door-to-needle times were 165 (95- 272) minutes and 38 (24-60) minutes, respectively. Generally, patients presenting with higher GRACE risk scores were treated with newer thrombolytic agents (reteplase and tenecteplase) (P < 0.001). The use of newer thrombolytic agents was associated with a significantly lower mortality at both 1-month (0.8% vs. 1.7% vs. 4.2%; P = 0.014) and 1-year (0% vs. 1.7% vs. 3.4%; P = 0.044) compared to streptokinase use.
Majority of STEMI patients from the Middle East were thrombolysed with streptokinase and reteplase in equal numbers. Nearly one-fifth of patients did not receive any reperfusion therapy. There was inappropriately long symptom-onset to hospital presentation as well as door-to-needle times. Use of newer thrombolytic agents in high risk patients was appropriate. Newer thrombolytic agents were associated with significantly lower mortality at 1-month and 1-year compared to the older agent, streptokinase.
Acute coronary syndrome; GRACE score; Middle East; mortality; reteplase; STEMI; streptokinase; tenecteplase; thrombolytic therapy
We evaluated prevalence and clinical outcome of polyvascular disease (PolyVD) in patients presenting with acute coronary syndrome (ACS). Data for 7689 consecutive ACS patients were collected from the 2nd Gulf Registry of Acute Coronary Events between October 2008 and June 2009. Patients were divided into 2 groups (ACS with versus without PolyVD). All-cause mortality was assessed at 1 and 12 months. Patients with PolyVD were older and more likely to have cardiovascular risk factors. On presentation, those patients were more likely to have atypical angina, high resting heart rate, high Killip class, and GRACE risk scoring. They were less likely to receive evidence-based therapies. Diabetes mellitus, renal failure, and hypertension were independent predictors for presence of PolyVD. PolyVD was associated with worse in-hospital outcomes (except for major bleedings) and all-cause mortality even after adjusting for baseline covariates. Great efforts should be directed toward primary and secondary preventive measures.
To evaluate clinical profiles, management and in-hospital outcomes of acute coronary syndrome (ACS) patients with metabolic syndrome (MetS) in the United Arab Emirates (UAE).
MetS was defined according to the criteria for its diagnosis by the International Diabetes Federation (IDF) and the American Heart Association/National Heart, Lung and Blood Institute (AHA/NHLBI). Participants were admitted to various hospitals in the UAE with a diagnosis of ACS in 2007 as part of the Gulf Registry of Acute Coronary Events (Gulf RACE) project. We compared baseline characteristics, treatment patterns, and in-hospital outcomes stratified by MetS status.
Of 1259 patients with ACS in the UAE (mean age: 52 ± 11 years, 88.8% males), the majority (n = 851, 67.6%) had MetS. MetS patients were more frequently males (86.4 vs 13.6%; P < 0.001). They were more obese (waist circumference and BMI, P < 0.001) as compared with non-MetS patients. MetS was more frequently associated with hypertension (51.1 vs 37.7%; P < 0.001) and diabetes mellitus (45.6 vs 24.3%; P < 0.001). After multivariate adjustment, certain MetS criteria rather than MetS itself were associated with higher in-hospital mortality and heart failure. Paradoxically, hypertension was associated with lower in-hospital mortality.
Prevalence of MetS among patients with ACS in our study population was high. Certain MetS criteria were associated with higher in-hospital mortality and heart failure.
acute coronary syndrome; Gulf Registry of Acute Coronary Events; metabolic syndrome; Middle East; obesity; United Arab Emirates.
We used prospective cohort data of patients with acute coronary syndrome (ACS) to compare their management on weekdays/mornings with weekends/nights, and the possible impact of this on 1-month and 1-year mortality. Analyses were evaluated using univariate and multivariate statistics. Of the 4,616 patients admitted to hospitals with ACS, 76% were on weekdays. There were no significant differences in 1-month (odds ratio (OR), 0.88; 95% CI: 0.68-1.14) and 1-year mortality (OR, 0.88; 95% CI: 0.70-1.10), respectively, between weekday and weekend admissions. Similarly, there were no significant differences in 1-month (OR, 0.92; 95% CI: 0.73-1.15) and 1-year mortality (OR, 0.98; 95% CI: 0.80-1.20), respectively, between nights and day admissions. In conclusion, apart from lower utilization of angiography (P < .001) at weekends, there were largely no significant discrepancies in the management and care of patients admitted with ACS on weekdays and during morning hours compared with patients admitted on weekends and night hours, and the overall 30-day and 1-year mortality was similar between both the cohorts.
Acute coronary syndrome; Weekend; Weekday; Mortality; Admission.
There is increasing interest to make primary data from published research publicly available. We aimed to assess the current status of making research data available in highly-cited journals across the scientific literature.
Methods and Results
We reviewed the first 10 original research papers of 2009 published in the 50 original research journals with the highest impact factor. For each journal we documented the policies related to public availability and sharing of data. Of the 50 journals, 44 (88%) had a statement in their instructions to authors related to public availability and sharing of data. However, there was wide variation in journal requirements, ranging from requiring the sharing of all primary data related to the research to just including a statement in the published manuscript that data can be available on request. Of the 500 assessed papers, 149 (30%) were not subject to any data availability policy. Of the remaining 351 papers that were covered by some data availability policy, 208 papers (59%) did not fully adhere to the data availability instructions of the journals they were published in, most commonly (73%) by not publicly depositing microarray data. The other 143 papers that adhered to the data availability instructions did so by publicly depositing only the specific data type as required, making a statement of willingness to share, or actually sharing all the primary data. Overall, only 47 papers (9%) deposited full primary raw data online. None of the 149 papers not subject to data availability policies made their full primary data publicly available.
A substantial proportion of original research papers published in high-impact journals are either not subject to any data availability policies, or do not adhere to the data availability instructions in their respective journals. This empiric evaluation highlights opportunities for improvement.
To evaluate changes in management practices and its influence on short term hospital outcomes in patients with acute myocardial infarction (AMI) admitted during two different time periods, 2007 and 2004.
Methods and Results:
We studied AMI patients from two acute coronary syndrome registries carried out in Kuwait in 2007 and 2004. We included 1872 and 1197 patients from the 2007 and 2004 registries, respectively. When compared with 2004, patients from the 2007 registry had similar baseline clinical characteristics. In 2007 compared to 2004, during the in-hospital period, patients with AMI received significantly more statins (94% vs. 73%%, p<0.0001), Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB) (70% vs. 47%, p<0.001), and Clopidogrel (38% vs. 4%, p<0.001), while beta-blockers use dropped in 2007 compared to 2004 (63% vs. 68%, p=0.0066). The rates of in-hospital mortality and recurrent ischemia were significantly lower in the 2007 cohort compared with the 2004 cohort (for mortality 2.2% vs. 3.9%, P=0.0008, for recurrent ischemia 13.7% vs. 20.4%, P=0<0.0001).Higher utilization of angiotensin converting enzyme inhibitors, angiotensin receptor blockers and statins were the main contributors to the improved in-hospital mortality and morbidity.
In the acute management of AMI, there was a significant increase in the use of statins, ACE inhibitors and Clopidogrel in 2007 compared to 2004. This was associated with a significant decrease in the in-hospital mortality and recurrent ischemia. Adherence to guidelines recommended therapies improved in-hospital outcomes.
Acute Coronary Syndrome; Outcomes; Evidence based therapies.
Acute Coronary Syndrome (ACS) can occur in patients with prior coronary artery bypass grafting (CABG). In the Gulf Registry of acute coronary events (Gulf RACE), we identified the clinical characteristics and in-hospital outcomes of these patients.
Clinical characteristics and in-hospital outcomes for 461 ACS patients with prior CABG are compared to 7715 ACS patients without prior CABG enrolled from 64 hospitals in 6 Gulf countries over a 6-month period.
The overall incidence of ACS with prior CABG was 5.6% out of 8176 patients. The ACS with prior CABG were older (63 vs 55 years, P<0.0001), had more history of diabetes (62.3 vs 37.6%, P <0.0001), dyslipidemia (70.3 vs 29.5%, P<0.0001), and hypertension (75.7 vs 47.8%, P<0.0001) compared with the non-CABG group. They presented more frequently with dyspnea (14.8 vs 9.5%, P<0.0005), non-ST segment elevation myocardial infarction (41.4 vs 31.6%, P<0.0001) and echocardiographic evidence of left ventricular dysfunction (49.4 vs 29.8%, P<0.0001) than ACS without prior CABG. They had a complicated in-hospital course with more recurrent ischemia (13.9 vs 9.3%, P=0.0011), heart failure (24.1 vs 15.7%), and stroke (2.2 vs 0.6%) compared with those without CABG. The in-hospital mortality rate was 5.6% in the CABG group compared with 3.5% in the ACS without prior CABG group. After adjusting for confounders, prior CABG was independently associated with recurrent ischemia and shock, more in patients presenting with ST elevation than non-ST elevation ACS.
Patients with ACS and prior CABG are a high-risk group with poor outcomes irrespective of their older age and comorbidities. They should be identified and treated differently to improve their outcomes.
Acute Coronary Syndrome; Angioplasty; Comorbidity; Coronary Artery Bypass Grafting; Risk factors; Stroke.
Over the last 20 years, percutaneous transluminal balloon coronary angioplasty (PTCA), bare metal stents (BMS) and drug eluting stents (DES) succeeded each other as catheter-based treatments for coronary artery disease (CAD). We present an overview of randomised trials comparing these interventions with each other and with medical therapy in patients with nonacute CAD.
We searched Medline for trials contrasting at least two of the aforementioned interventions. Outcomes of interest were death, myocardial infarction (MI), coronary artery bypass grafting (CABG), target lesion or vessel revascularisation (TLR/TVR), and any revascularisation. Random effects meta-analyses summarised head-to-head (direct) comparisons, and network meta-analyses integrated direct and indirect evidence.
61 eligible trials (25 388 patients) investigated 4 of 6 possible comparisons between the 4 interventions. No trials directly compared DES with medical therapy or PTCA. In all direct or indirect comparisons, succeeding advancements in PCI did not yield detectable improvements in deaths and MI. The risk ratio for indirect comparisons between DES and medical therapy was 0·96 (95% confidence interval: 0·60, 1·52) for death and 1·15 (0·73, 1·82) for MI. In contrast, there were sequential significant reductions in TLR/TVR with BMS compared to PTCA and with DES compared to BMS. The risk ratio for the indirect comparison between DES and PTCA for TLR/TVR was 0·30 (0·17, 0·51).
Sequential innovations in the catheter-based treatment of nonacute CAD showed no evidence of an impact on death or MI when compared with medical therapy.
Atrial fibrillation (AF) is the most common sustained arrhythmia and a challenging clinical problem encountered in daily clinical practice. There is an increasing body of evidence linking inflammation to a broad spectrum of cardiovascular conditions including AF. Historical evidence supports an association between AF and inflammation and is consistent with the association of AF with inflammatory conditions of the heart, such as myocarditis and pericarditis. AF has been associated with myocardial oxidative stress, and antioxidant agents have demonstrated antiarrhythmic benefit in humans. Increased plasma interleukin (IL)-6, C-reactive protein (CRP), and plasma viscosity support the existence of an inflammatory state among “typical” populations with chronic AF. These indexes of inflammation are related to the prothrombotic state and may be linked to the clinical characteristics of the patients (underlying vascular disease and comorbidities), rather than simply to the presence of AF itself. It has been suggested that inflammation may have a role in the development of atrial arrhythmias after cardiac surgery, and that a genetic predisposition to develop postoperative complications exists. Cytokines can have a prognostic significance; IL-6 levels, CRP, and other cytokines may have prognostic value in AF. Cytokine lowering therapies, statins, angiotensin converting enzyme inhibitors and other anti-inflammatory agents may have a role in the treatment of AF. The present article provides an overview of the evidence linking inflammatory cytokines to AF and their therapeutic and prognostic implications.
atrial fibrillation; inflammation; cytokines
Patent foramen ovale (PFO) is significantly associated with cryptogenic stroke (CS). However, even in patients with CS, a PFO can be an incidental finding. We sought to estimate the probability that a PFO in a patient with CS is incidental.
A systematic search identified 23 case-control studies examining the prevalence of PFO in patients with CS versus controls with stroke of known-cause. Using simple assumptions and Bayes’ theorem we calculated the probability a PFO is incidental in patients with CS. Random effects meta-analyses estimated the odds ratio (OR) of a PFO in CS versus controls in different age populations, with or without atrial septal aneurysms (ASA), and were used to summarize across studies the probability that a PFO in CS is incidental.
The summary OR (95% confidence limits) for PFO in CS versus controls was 2.9 (CI 2.1, 4.0). The corresponding ORs for young and old patients (< or ≥ 55 years) were 5.1 (3.3, 7.8) and 2.0 (1.0, 3.7), respectively. The corresponding probabilities that a PFO in patients with CS is incidental were 33% (28%, 39%) in age-inclusive studies, 20% (16%, 25%) in younger patients, and 48% (34%, 66%) in older patients. These probabilities were much lower when an ASA was present.
In patients with otherwise CS, approximately a third of discovered PFOs are likely to be incidental, and hence not benefit from closure. This probability is sensitive to patient characteristics such as age and the presence of an ASA, suggesting the importance of patient-selection in therapeutic decision-making.
Patent foramen ovale; Risk factors for stroke; Secondary stroke prevention
We evaluated the prognostic significance of prolonged QRS duration (QRSd) relative to arrhythmic outcomes in medically- and implantable cardioverter-defibrillator (ICD)-treated patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II.
There is conflicting literature on the relationship between prolonged QRSd and arrhythmic events, including sudden cardiac death (SCD), in heart failure patients with or without ICDs.
Using a Cox-proportional hazards model adjusting for ejection fraction (EF), heart failure class, and blood urea nitrogen, we estimated the association of prolonged QRSd ≥ 140 milliseconds with SCD in the medically-treated arm, and SCD or first ICD therapy for rapid ventricular tachycardia/fibrillation (VT/VF, cycle length ≤ 260 ms) in the ICD-treated arm.
In the medically-treated arm, prolonged QRSd was a significant independent predictor of SCD (HR 2.12 [95% CI 1.20–3.76], p = 0.01). However, in the ICD-treated arm, prolonged QRSd did not predict SCD or rapid VT/VF (HR 0.77 [95% CI 0.47–1.24], p = 0.28). The difference in the prognostic effect of prolonged QRSd in these two groups was significant (p<0.01). These results were not affected by varying the cycle length defining rapid VT/VF or the duration defining QRSd prolongation.
In patients with prior myocardial infarction and EF ≤ 30%, prolonged QRSd does not predict SCD/VT/VF in ICD-treated patients, but does predict SCD in medically-treated patients. This underscores the non-equivalence of VT/VF and SCD, and the need for caution in inferring risk of SCD when using non-randomized databases that include only patients with ICDs.
Death; sudden; defibrillation; tachyarrhythmias; risk factors; QRS duration
It has been demonstrated that patients enrolled in clinical trials frequently have a large degree of variation in their baseline risk for the outcome of interest. Thus, some have suggested that clinical trial results should routinely be stratified by outcome risk using risk models, since the summary results may otherwise be misleading. However, variation in competing risk is another dimension of risk heterogeneity that may also underlie treatment effect heterogeneity. Understanding the effects of competing risk heterogeneity may be especially important for pragmatic comparative effectiveness trials, which seek to include traditionally excluded patients, such as the elderly or complex patients with multiple comorbidities. Indeed, the observed effect of an intervention is dependent on the ratio of outcome risk to competing risk, and these risks – which may or may not be correlated – may vary considerably in patients enrolled in a trial. Further, the effects of competing risk on treatment effect heterogeneity can be amplified by even a small degree of treatment related harm. Stratification of trial results along both the competing and the outcome risk dimensions may be necessary if pragmatic comparative effectiveness trials are to provide the clinically useful information their advocates intend.
Sudden arrhythmic death as a result of a blunt chest wall blow has been termed Commotio Cordis (CC). CC is being reported with increasing frequency with more than 180 cases now described in the United States Commotio Cordis Registry. The clinical spectrum is diverse; however young athletes tend to be most at risk, with victims commonly being struck by projectiles regarded as standard implements of the sport. Sudden death is instantaneous and victims are most often found in ventricular fibrillation (VF). Chest blows are not of sufficient magnitude to cause any significant damage to overlying thoracic structures and autopsy is notable for the absence of any structural cardiac injury. Development of an experimental model has allowed for substantial insights into the underlying mechanisms of sudden death. In anesthetized juvenile swine, induction of VF is instantaneous following chest impacts that occur during a vulnerable window before the T wave peak. Other critical variables, including the impact velocity and location, and the hardness of the impact object have also been identified. Rapid left ventricular pressure rise following chest impact likely results in activation of ion channels via mechano-electric coupling. The generation of inward current through mechano-sensitive ion channels results in augmentation of repolarization and non-uniform myocardial activation, and is the cause of premature ventricular depolarizations that are triggers of VF in CC. Currently available chest protectors commonly used in sport are not adequately designed to prevent CC. The development of more effective chest protectors and the widespread availability of automated external defibrillators at youth sporting events could improve the safety of young athletes.
Commotio cordis; Ventricular Fibrillation; Athletes; Sudden Death; Mechano-electric coupling