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1.  Lumen and calcium characteristics within calcified coronary lesions. Comparison of computed tomography coronary angiography versus intravascular ultrasound 
Computed tomography coronary angiography (CTCA) is a diagnostic method used for exclusion of coronary artery disease. However, lower accuracy of CTCA in assessment of calcified lesions is a significant factor impeding applicability of CTCA for assessment of coronary atherosclerosis.
To provide insight into lumen and calcium characteristics assessed with CTCA, we compared these parameters to the reference of intravascular ultrasound (IVUS).
Material and methods
Two hundred and fifty-two calcified lesions within 97 arteries of 60 patients (19 women, age 63 ±10 years) underwent assessment with both 2 × 64 slice CT (Somatom Definition, Siemens) and IVUS (s5, Volcano Corp.). Coronary lumen and calcium dimensions within calcified lesions were assessed with CTCA and compared to the reference measurements made with IVUS.
On average CTCA underestimated mean lumen diameter (2.8 ±0.7 mm vs. 2.9 ±0.8 mm for IVUS), lumen area (6.4 ±3.4 mm2 vs. 7.0 ±3.7 mm2 for IVUS, p < 0.001) and total calcium arc (52 ±35° vs. 83 ±54°). However, analysis of tertiles of the examined parameters revealed that the mean lumen diameter, lumen area and calcium arc did not significantly differ between CTCA and IVUS within the smallest lumens (1st tertile of mean lumen diameter at 2.1 mm, and 1st tertile of lumen area at 3.7 mm2) and lowest calcium arc (mean of 40°).
Although, on average, CTCA underestimates lumen diameter and area as well as calcium arc within calcified lesions, the differences are not significant within the smallest vessels and calcium arcs. The low diagnostic accuracy of CTCA within calcified lesions may be attributed to high variance and not to systematic error of measurements.
PMCID: PMC3915947  PMID: 24570686
computed tomography; intravascular ultrasound; coronary angiography; coronary artery disease
2.  Intravascular Ultrasound to Guide Percutaneous Coronary Interventions 
Executive Summary
The objective of this health technology policy assessment was to determine the effectiveness and cost-effectiveness of using intravascular ultrasound (IVUS) as an adjunctive imaging tool to coronary angiography for guiding percutaneous coronary interventions.
Intravascular Ultrasound
Intravascular ultrasound is a procedure that uses high frequency sound waves to acquire 3-dimensional images from the lumen of a blood vessel. The equipment for performing IVUS consists of a percutaneous transducer catheter and a console for reconstructing images. IVUS has been used to study the structure of the arterial wall and nature of atherosclerotic plaques, and obtain measurements of the vessel lumen. Its role in guiding stent placement is also being investigated. IVUS is presently not an insured health service in Ontario.
Clinical Need
Coronary artery disease accounts for approximately 55% of cardiovascular deaths, the leading cause of death in Canada. In Ontario, the annual mortality rate due to ischemic heart disease was 141.8 per 100,000 population between 1995 and 1997. Percutaneous coronary intervention (PCI), a less invasive approach to treating coronary artery disease, is used more frequently than coronary bypass surgery in Ontario. The number of percutaneous coronary intervention procedures funded by the Ontario Ministry of Health and Long-term Care is expected to increase from approximately 17, 780 in 2004/2005 to 22,355 in 2006/2007 (an increase of 26%), with about 95% requiring the placement of one or more stents. Restenosis following percutaneous coronary interventions involving bare metal stents occurs in 15% to 30% of the cases, mainly because of smooth muscle proliferation and migration, and production of extracellular matrix. In-stent restenosis has been linked to suboptimal stent expansion and inadequate lesion coverage, while stent thrombosis has been attributed to incomplete stent-to-vessel wall apposition. Since coronary angiography (the imaging tool used to guide stent placement) has been shown to be inaccurate in assessing optimal stent placement, and IVUS can provide better views of the vessel lumen, the clinical utility of IVUS as an imaging tool adjunctive to coronary angiography in coronary intervention procedures has been explored in clinical studies.
A systematic review was conducted to answer the following questions:
What are the procedure-related complications associated with IVUS?
Does IVUS used in conjunction with angiography to guide percutaneous interventions improve patient outcomes compared to angiographic guidance without IVUS?
Who would benefit most in terms of clinical outcomes from the use of IVUS adjunctive to coronary angiography in guiding PCIs?
What is the effectiveness of IVUS guidance in the context of drug-eluting stents?
What is the cost-effectiveness ratio and budget impact of adjunctive IVUS in PCIs in Ontario?
A systematic search of databases OVID MEDLINE, EMBASE, MEDLINE In-Process & Other Non-Indexed Citations, The Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) database for the period beginning in May 2001 until the day of the search, November 4, 2005 yielded 2 systematic reviews, 1 meta-analysis, 6 randomized controlled trials, and 2 non-randomized studies on left main coronary arteries. The quality of the studies ranged from moderate to high. These reports were combined with reports from a previous systematic review for analysis. In addition to qualitative synthesis, pooled analyses of data from randomized controlled studies using a random effect model in the Cochrane Review Manager 4.2 software were conducted when possible.
Findings of Literature Review & Analysis
Intravascular ultrasound appears to be a safe tool when used in coronary interventions. Periprocedural complications associated with the use of IVUS in coronary interventions ranged from 0.5% in the largest study to 4%. Coronary rupture was reported in 1 study (1/54). Other complications included prolonged spasms of the artery after stenting, dissection, and femoral aneurysm.
Based on pooled analyses of data from randomized controlled studies, the use of intravascular ultrasound adjunctive to coronary intervention in percutaneous coronary interventions using bare metal stents yielded the following findings:
For lesions predominantly at low risk of restenosis:
There were no significant differences in preintervention angiographic minimal lumen diameter between the IVUS-guided and angiography-guided groups.
IVUS guidance resulted in a significantly larger mean postintervention angiographic minimal lumen diameter (weighted mean difference of 0.11 mm, P = .0003) compared to angiographic guidance alone.
The benefit in angiographic minimal lumen diameter from IVUS guidance was not maintained at 6-month follow-up, when no significant difference in angiographic minimal lumen diameter could be detected between the two arms (weighted mean difference 0.08, P = .13).
There were no statistically significant differences in angiographic binary restenosis rates between IVUS-guidance and no IVUS guidance (Odds ratio [OR] 0.87 in favour of IVUS, 95% Confidence Interval [CI] [0.64–1.18], P = 0.37).
IVUS guidance resulted in a reduction in the odds of target lesion revascularization (repeat percutaneous coronary intervention or coronary bypass graft) compared to angiographic guidance alone. The reduction was statistically significant at a follow-up period of 6 months to 1 year, and at a follow-up period of 18 month to 2 years (OR 0.52 in favour of IVUS, 95% CI [0.33–0.81], P = .004).
Total revascularization rate (either target lesion or target vessel revascularization) was significantly lower for IVUS-guided patients at 18 months to 2.5 years after intervention (OR 0.43 in favour of IVUS, 95% CI [0.29–0.63], p < .0001).
There were no statistically significant differences in the odds of death (OR 1.36 in favour of no IVUS, P =0.65) or myocardial infarction (OR 0.95 in favour of IVUS, P = 0.93) between IVUS-guidance and angiographic guidance alone at up to 2.5 years of follow-up
The odds of having a major cardiac event (defined as death, myocardial infarction, and target lesion or target vessel revascularization) were significantly lower for patients with IVUS guidance compared to angiographic guidance alone during follow-up periods of up to 2.5 years (OR 0.53, 95% CI [0.36–0.78], P = 0.001). Since there were no significant reductions in the odds of death or myocardial infarction, the reduction in the odds of combined events reflected mainly the reduction in revascularization rates.
For lesions at High Risk of Restenosis:
There is evidence from one small, randomized controlled trial (n=150) that IVUS-guided percutaneous coronary intervention in long de novo lesions (>20 mm) of native coronary arteries resulted in statistically significant larger minimal lumen Diameter, and statistically significant lower 6-month angiographic binary restenosis rate. Target vessel revascularization rate and the rate of combined events were also significantly reduced at 12 months.
A small subgroup analysis of a randomized controlled trial reported no benefit in clinical or angiographic outcomes for IVUS-guided percutaneous coronary interventions in patients with diabetes compared to those guided by angiography. However, due to the nature and size of the analysis, no firm conclusions could be reached.
Based on 2 small, prospective, non-randomized controlled studies, IVUS guidance in percutaneous coronary interventions of left main coronary lesions using bare metal stents or drug-eluting stents did not result in any benefits in angiographic or clinical outcomes. These findings need to be confirmed.
Interventions Using Drug-Eluting Stents
There is presently no evidence on whether the addition of IVUS guidance during the implantation of drug-eluting stents would reduce incomplete stent apposition, or improve the angiographic or clinical outcomes of patients.
Ontario-Based Economic Analysis
Cost-effectiveness analysis showed that PCIs using IVUS guidance would likely be less costly and more effective than PCIs without IVUS guidance. The upfront cost of adjunctive use of IVUS in PCIs ranged from $1.56 million at 6% uptake to $13.04 million at 50% uptake. Taking into consideration cost avoidance from reduction in revascularization associated with the use of IVUS, a net saving of $0.63 million to $5.2 million is expected. However, since it is uncertain whether the reduction in revascularization rate resulting from the use of IVUS can be generalized to clinical settings in Ontario, further analysis on the budget impact and cost-effectiveness need to be conducted once Ontario-specific revascularization rates are verified.
Factors to be Considered in the Ontario Context
Applicability of Findings to Ontario
The interim analysis of an Ontario field evaluation that compared drug-eluting stents to bare metal stents showed that the revascularization rates in low-risk patients with bare metal stents were much lower in Ontario compared to rates reported in randomized controlled trials (7.2% vs >17 %). Even though IVUS is presently not routinely used in the stenting of low-risk patients in Ontario, the revascularization rates in these patients in Ontario were shown to be lower than those reported for the IVUS groups reported in published studies. Based on this information and previous findings from the Ontario field evaluation on stenting, it is uncertain whether the reduction in revascularization rates from IVUS guidance can be generalized to Ontario. In light of the above findings, it is advisable to validate the reported benefits of IVUS guidance in percutaneous coronary interventions involving bare metal stents in the Ontario context.
Licensing Status
As of January 16, 2006, Health Canada has licensed 10 intravascular ultrasound imaging systems/catheters for transluminal intervention procedures, most as class 4 medical devices.
Current Funding
IVUS is presently not an insured procedure under the Ontario Health Insurance Plan and there are no professional fees for this procedure. All costs related to the use of IVUS are covered within hospitals’ global budgets. A single use IVUS catheter costs approximately $900CDN and the procedure adds approximately 20 minutes to 30 minutes to a percutaneous coronary intervention procedure.
According to an expert consultant, current use of IVUS in coronary interventions in Ontario is probably limited to high-risk cases such as interventions in long lesions, small vessels, and bifurcated lesions for which images from coronary angiography are indeterminate. It was estimated that IVUS is being used in about 6% of all percutaneous coronary interventions at a large Ontario cardiac centre.
Expert Opinion
IVUS greatly enhances the cardiac interventionists’ ability to visualize and assess high-risk lesions such as long lesions, narrow lesions, and bifurcated lesions that may have indeterminate angiographic images. Information from IVUS in these cases facilitates the choice of the most appropriate approach for the intervention.
The use of adjunctive IVUS in PCIs using bare metal stents in lesions predominantly at low risk for restenosis had no significant impact on survival, myocardial infarction, or angiographic restenosis rates up to 2.5 years after intervention.
The use of IVUS adjunctive to coronary angiography in percutaneous coronary interventions using bare metal stents in lesions predominantly at low risk for restenosis significantly reduced the target lesion and target vessel revascularization at a follow-up period of 18 months to 2.5 years.
One small study suggests that adjunctive IVUS in PCIs using bare metal stents in long lesions (>20 mm) significantly improved the 6-month angiographic restenosis rate and one-year target lesion revascularization rate. These results need to be confirmed with large randomized controlled trials.
Based on information from the Ontario field evaluation on stenting, it is uncertain whether the reduction in revascularization rate resulting from the use of IVUS in the placement of bare metal stents can be generalized to clinical settings in Ontario.
There is presently insufficient evidence available to determine the impact of adjunctive IVUS in percutaneous interventions in high-risk lesions (other than long lesions) or in PCIs using drug-eluting stents.
PMCID: PMC3379536  PMID: 23074482
3.  Dual imaging stress echocardiography versus computed tomography coronary angiography for risk stratification of patients with chest pain of unknown origin 
Dual imaging stress echocardiography, combining the evaluation of wall motion and coronary flow reserve (CFR) on the left anterior descending artery (LAD), and computed tomography coronary angiography (CTCA) are established techniques for assessing prognosis in chest pain patients. In this study we compared the prognostic value of the two methods in a cohort of patients with chest pain having suspected coronary artery disease (CAD).
A total of 131 patients (76 men; age 68 ± 9 years) with chest pain of unknown origin underwent dipyridamole (up to 0.84 mg/kg over 6 min) stress echo with CFR assessment of LAD by Doppler and CTCA. A CFR ≤ 1.9 was considered abnormal, while > 50% lumen diameter reduction was the criterion for significant CAD at CTCA.
Of 131 patients, 34 (26%) had ischemia at stress echo (new wall motion abnormalities), and 56 (43%) had reduced CFR on LAD. Significant coronary stenosis at CTCA was found in 69 (53%) patients. Forty-six patients (84%) with abnormal CFR on LAD showed significant CAD at CTCA (p < 0.001). Calcium score was higher in patients with reduced than in those with normal CFR (265 ± 404 vs 131 ± 336, p = 0.04). During a median follow-up of 7 months (1st to 3rd quartile: 5–13 months), there were 45 major cardiac events (4 deaths, 11 nonfatal myocardial infarctions, and 30 late [≥6 months] coronary revascularizations). At Cox analysis, independent prognostic indicators were calcium score > 100 (HR 2.84, 95% CI 1.33-6.07, p = 0.007), significant CAD at CTCA (HR 2.68, 95% CI 1.23-5.82, p = 0.013), and inducible ischemia or CFR <1.9R on LAD on dual imaging stress echo (HR 2.25, 95% CI 1.05-4.84, p = 0.038).
Functional and anatomical evaluation using, respectively, dual imaging stress echocardiography and CTCA are both effective modalities to risk stratify patients with chest pain of unknown origin, yielding independent and comparable prognostic value. Compared to CTCA, however, stress echocardiography has the advantage of lower cost and of being free of radiations.
PMCID: PMC4409769  PMID: 25896850
Coronary flow reserve; Computed tomography coronary angiography; Coronary artery disease
4.  Clinical applications of intravascular ultrasound (IVUS): experience from an academic high volume centre of Northern Greece 
Hippokratia  2011;15(1):60-63.
Background: Intravascular ultrasound (IVUS) has become a valuable tool adjunctive to coronary angiography due to its ability to directly image atheroma and the vessel wall. We aimed to evaluate the use of IVUS during diagnostic angiography and coronary interventions in a coronary intervention academic high volume center of northern Greece.
Patients and Methods: IVUS studies have been retrospectively retrieved from 2005 to 2008 from the archives of the catheterization laboratory of our department. IVUS was performed in 403 patients (294 male) of mean age 62±6 years. Indications for coronary angiography +/- intervention were acute coronary syndromes (49%), stable angina (46%) and previous coronary angioplasty evaluation (5%).
Results: Forty eight per cent of the IVUS studies were performed in left anterior descending artery (LAD), 25% in right coronary artery (RCA), 18% in left circumflex artery (LCx), and the rest (9%) in left main coronary artery (LMCA) or in coronary branches. Indications for performing an IVUS study were assessment of intermediate lesions (60%), evaluation of stent placement (36.5%), and determination of stent restenosis aetiology (3.5%). Among studies performed for assessment of intermediate lesions, 63% showed a non critical stenosis. IVUS after coronary stenting revealed a suboptimal stent placement in 77% of the cases, while in cases of stent restenosis, IVUS showed inadequate initial stent deployment in 43% of the patients.
Conclusions: The use of IVUS in our department has contributed to the optimization of intervertional treatment of coronary lesions by means of evaluating borderline lesions, stenting placement and stent restenosis.
PMCID: PMC3093147  PMID: 21607038
intravascular ultrasound; intermediate lesions; coronary angioplasty; optimal stent placement; restenosis
5.  Diagnostic performance of exercise bicycle testing and single-photon emission computed tomography: comparison with 64-slice computed tomography coronary angiography 
To conduct a comparison of the diagnostic performance of exercise bicycle testing and single-photon emission computed tomography (SPECT) with computed tomography coronary angiography (CTCA) for the detection of obstructive coronary artery disease (CAD) in patients with stable angina. 376 symptomatic patients (254 men, 122 women, mean age 60.4 ± 10.0 years) referred for noninvasive stress testing (exercise bicycle test and/or SPECT) and invasive coronary angiography were included. All patients underwent additional 64-slice CTCA. The diagnostic performance of exercise bicycle testing (ST segment depression), SPECT (reversible perfusion defect) and CTCA (≥50% lumen diameter reduction) was presented as sensitivity, specificity, positive and negative predictive value (PPV and NPV) to detect or rule out obstructive CAD with quantitative coronary angiography as reference standard. Comparisons of exercise bicycle testing versus CTCA (n = 334), and SPECT versus CTCA (n = 61) were performed. The diagnostic performance of exercise bicycle testing was significantly (P value < 0.001) lower compared to CTCA: sensitivity of 76% (95% CI, 71–82) vs. 100% (95% CI, 97–100); specificity of 47% (95% CI, 36–58) vs. 74% (95% CI, 63–82). We observed a PPV of 70% (95% CI, 65–75) vs. 91% (95% CI, 87-94); and NPV of 30% (95%, 25–35) vs. 99% (95%, 90–100). There was a statistically significant difference in sensitivity (P value < 0.05) between SPECT and CTCA: 89% (95% CI, 75–96) vs. 98% (95% CI, 87–100); but not in specificity (P value > 0.05): 77% (95% CI, 50–92) vs. 82% (95% CI, 56–95). We observed a PPV of 91% (95% CI, 77–97) vs. 93% (95% CI, 81–98); and NPV of 72% (95%, 46–89) vs. 93% (95%, 66–100). SPECT and CTCA yielded higher diagnostic performance compared to traditional exercise bicycle testing for the detection and rule out of obstructive CAD in patients with stable angina.
PMCID: PMC3326370  PMID: 21222035
Exercise bicycle testing; Single-photon emission computed tomography; SPECT; Computed tomography coronary angiography; CT; Diagnostic accuracy
6.  Computed tomography coronary angiography accuracy in women and men at low to intermediate risk of coronary artery disease 
European Radiology  2012;22(11):2415-2423.
To investigate the diagnostic accuracy of CT coronary angiography (CTCA) in women at low to intermediate pre-test probability of coronary artery disease (CAD) compared with men.
In this retrospective study we included symptomatic patients with low to intermediate risk who underwent both invasive coronary angiography and CTCA. Exclusion criteria were previous revascularisation or myocardial infarction. The pre-test probability of CAD was estimated using the Duke risk score. Thresholds of less than 30 % and 30–90 % were used for determining low and intermediate risk, respectively. The diagnostic accuracy of CTCA in detecting obstructive CAD (≥50 % lumen diameter narrowing) was calculated on patient level. P < 0.05 was considered significant.
A total of 570 patients (46 % women [262/570]) were included and stratified as low (women 73 % [80/109]) and intermediate risk (women 39 % [182/461]). Sensitivity, specificity, PPV and NPV were not significantly different in and between women and men at low and intermediate risk. For women vs. men at low risk they were 97 % vs. 100 %, 79 % vs. 90 %, 80 % vs. 80 % and 97 % vs. 100 %, respectively. For intermediate risk they were 99 % vs. 99 %, 72 % vs. 83 %, 88 % vs. 93 % and 98 % vs. 99 %, respectively.
CTCA has similar diagnostic accuracy in women and men at low and intermediate risk.
Key Points
• Coronary artery disease (CAD) is increasingly investigated by computed tomography angiography (CTCA).
• CAD detection or exclusion by CTCA is not different between sexes.
• CTCA diagnostic accuracy was similar between low and intermediate risk sex-specific-groups.
• CTCA rarely misses obstructive CAD in low–intermediate risk women and men.
• CAD yield by invasive coronary angiography after positive CTCA is similar between sex-risk-specific groups.
PMCID: PMC3472076  PMID: 22669338
Diagnostic accuracy; CT coronary angiography; Multidetector computed tomography; Coronary artery disease; Duke pre-test probability; Sex, women and men
7.  Dual-source CT coronary angiographic evaluation of coronary artery fistulas 
The aim of the present study was to retrospectively evaluate the incidence and morphological features of coronary artery fistulas (CAFs) detected by dual-source computed tomography coronary angiography (DS-CTCA). Between January 2011 and January 2013, 19,584 consecutive patients that had undergone electrocardiogram-triggering DS-CTCA were retrospectively reviewed. Image reconstructions were performed and image quality was evaluated. The medical information of the patients with CAF was reviewed from the medical records. Among the 19,584 patients, 66 patients were diagnosed with CAFs by CTCA, including 60 patients with coronary pulmonary artery fistulas (CPAFs) and six with coronary left ventricular fistulas. Therefore, the incidence of CAFs was 0.34%. Image quality was considered to be excellent in 61 patients and moderate in five cases. CPAFs were identified as small and tortuous vessels in 24 patients and dilated vessels close to the surface of the pulmonary artery (PA) in 36 patients. The coronary left ventricular fistulas were identified as dilated vessels that were draining into the posterior wall of the left ventricle. Among the 66 patients, 54 patients had one traceable fistula and the remaining 12 patients were shown to have two fistula vessels. The average diameter of the detected fistulas, measured with CTCA, was 3.1±1.9 mm. A high-density flow jet of contrast agent shunting from the fistula into the low density PA was observed in 46 patients with CPAF. The results indicate that DS-CTCA is a reliable noninvasive tool that allows the accurate delineation of CAFs.
PMCID: PMC3991497  PMID: 24940403
coronary artery fistula; dual-source computed tomography; computed tomography coronary angiography
8.  Is there a role for CT coronary angiography in patients with symptomatic angina? Effect of coronary calcium score on identification of stenosis 
Present guidelines discourage the use of CT coronary angiography (CTCA) in symptomatic angina patients. We examined the relation between coronary calcium score (CS) and the performance of CTCA in patients with stable and unstable angina in order to understand under which conditions CTCA might be a gate-keeper to conventional coronary angiography (CCA) in such patients. We included 360 patients between 50 and 70 years old with stable and unstable angina who were clinically referred for CCA irrespective of CS. Patients received CS and CCTA on 64-slice scanners in a multicenter cross-sectional trial. The institutional review board approved the study. Diagnostic performance of CTCA to detect or rule out significant coronary artery disease was calculated on a per patient level in pre-defined CS categories. The prevalence of significant coronary artery disease strongly increased with CS. Negative CTCA were associated with a negative likelihood ratio of <0.1 independent of CS. Positive CTCA was associated with a high positive likelihood ratio of 9.4 if CS was <10. However, for higher CS the positive likelihood ratio never exceeded 3.0 and for CS >400 it decreased to 1.3. In the 62 (17%) patients with CS <10, CTCA reliably identified the 42 (68%) of these patients without significant CAD, at no false negative CTCA scans. In symptomatic angina patients, a negative CTCA reliably excludes significant CAD but the additional value of CTCA decreases sharply with CS >10 and especially with CS >400. In patients with CS <10, CTCA provides excellent diagnostic performance.
PMCID: PMC2784513  PMID: 19649721
Computed tomography; Coronary angiography; Diagnostic performance; Calcium score
9.  Indirect Radionuclide Coronary Angiography to Evaluate Gradients of Myocardial Blood Flow and Flow Reserve Through Coronary Stenosis Using N-13 Ammonia PET/CT 
Chonnam Medical Journal  2013;49(2):69-74.
Although quantitative evaluation of myocardial blood flow (MBF) and myocardial flow reserve (MFR) has been perceived as an attractive advantage of positron emission tomography (PET) over other cardiac imaging technologies, application of the information to specific coronary lesions is a difficult task for nuclear cardiologists. We hypothesized that changes in MBF and MFR over a coronary lesion could be identified by use of a hybrid technology of CT coronary angiography (CTCA) and N-13 ammonia PET. To evaluate this hypothesis, we measured the gradient of MBF and MFR through coronary stenosis in seven patients (M:F=3:4, median age 56 years) with coronary artery disease who underwent N-13 ammonia PET, CTCA, and interventional coronary angiography. Two patients had proximal left anterior descending (LAD) coronary artery disease and five patients had mid to distal LAD disease. Mean global stress and rest MBF were 2.62±0.58 and 1.03±0.19 ml/min/g, respectively. Mean global MFR was 2.6±0.73. Regional stress and rest MBF in the LAD territory were 2.36±0.75 and 0.96±0.21 ml/min/g, respectively. Regional MFR in the LAD territory was 2.55±0.83 ml/min/g. Stress MBF changed dramatically according to the location of coronary stenosis. It dropped acutely in proximal lesions, whereas it diminished gradually in mid to distal lesions. In conclusion, by use of a hybrid technology of CTCA and PET, it was feasible to make a direct correlation of coronary lesions with the gradient of MFR and CFR through coronary stenosis, which indicated the severity of the coronary lesion. We named this technique indirect radionuclide coronary angiography.
PMCID: PMC3759685  PMID: 24010069
Radionuclide imaging; Coronary angiography; Mycocardium
10.  Relation between coronary plaque calcium deposits as described by computed tomography coronary angiography and acute results of stent deployment as assessed by intravascular ultrasound 
The findings from intravascular ultrasound studies on the impact of calcium deposits on the results of stent implantation are conflicting.
To evaluate whether calcium deposits as assessed by (CTCA) influence results of stent deployment.
Material and methods
The study population comprised 60 patients (43 male; age 64.2 ±8.6 years) who underwent CTCA before stent implantation. Lesion calcium score, total calcium length, and maximal area and maximal thickness of calcium deposits within the lesion segment were assessed. Plaques were divided into those with calcium score ≥ median (group 1), calcium score < median (group 2), and without calcium (group 3). Intravascular ultrasound (IVUS) was performed after attainment of optimal angiographic results of the stent procedure. Focal and diffuse stent expansion was defined as either minimum stent area (MSA) or mean stent area over the length of the stent divided by reference lumen area.
The proximal reference segments of lesions with higher calcium score contained a larger plaque burden (47 ±12% vs. 41 ±9% vs. 34 ±18%, p = 0.02) – respectively for groups 1, 2, and 3. Positive correlation was observed between lesion calcium score and frequency of post-dilation (R = 0.28, p = 0.03). There was no difference in focal stent expansion (71 ±14% vs. 65 ±15% vs.71 ±15%, p = 0.3) or diffuse stent expansion (92 ±30% vs. 85 ±30% vs. 93 ±38%, p = 0.7) comparing groups 1, 2, and 3. Lesion calcium score, total length of calcium, and maximum area and thickness of calcium deposits did not correlate with focal or diffuse stent expansion.
Lesions with a higher CTCA calcium score had larger reference plaque burden after stent implantation and more likely required post-dilation, but final stent expansion as assessed by IVUS was not affected by the amount of CTCA calcium provided an angiographically optimal result was achieved.
PMCID: PMC3915965  PMID: 24570702
computed tomography coronary angiography; calcium deposits
11.  Observer variability in the assessment of CT coronary angiography and coronary artery calcium score: substudy of the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial 
Open Heart  2015;2(1):e000234.
Observer variability can influence the assessment of CT coronary angiography (CTCA) and the subsequent diagnosis of angina pectoris due to coronary heart disease.
We assessed 210 CTCAs from the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial for intraobserver and interobserver variability. Calcium score, coronary angiography and image quality were evaluated. Coronary artery disease was defined as none (<10%), mild (10–49%), moderate (50–70%) and severe (>70%) luminal stenosis and classified as no (<10%), non-obstructive (10–70%) or obstructive (>70%) coronary artery disease. Post-CTCA diagnosis of angina pectoris due to coronary heart disease was classified as yes, probable, unlikely or no.
Patients had a mean body mass index of 29 (28, 30) kg/m2, heart rate of 58 (57, 60)/min and 62% were men. Intraobserver and interobserver agreements for the presence or absence of coronary artery disease were excellent (95% agreement, κ 0.884 (0.817 to 0.951) and good (91%, 0.791 (0.703 to 0.879)). Intraobserver and interobserver agreement for the presence or absence of angina pectoris due to coronary heart disease were excellent (93%, 0.842 (0.918 to 0.755) and good (86%, 0.701 (0.799 to 0.603)), respectively. Observer variability of calcium score was excellent for calcium scores below 1000. More segments were categorised as uninterpretable with 64-multidetector compared to 320-multidetector CTCA (10.1% vs 2.6%, p<0.001) but there was no difference in observer variability.
Multicentre multidetector CTCA has excellent agreement in patients under investigation for suspected angina due to coronary heart disease.
Trial registration number
PMCID: PMC4442169  PMID: 26019881
12.  Lidocaine bolus may facilitate computed tomographic coronary angiography in patients with frequent premature ventricular contractions 
Heart rate irregularities are the major limitations of computed tomographic coronary angiography (CTCA) due to severe motion artifacts.
To evaluate the safety and efficacy of a lidocaine intravenous bolus in preserving good image quality by the transient suppression of premature ventricular contractions (PVC) during the CTCA scan.
Material and methods
The study group comprised 67 consecutive patients with sinus rhythm and numerous PVC scheduled for CTCA. Intravenous boluses of 25–50 mg lidocaine were given after calcium score assessment and immediately before CTCA. The control group comprised 67 patients with sinus rhythm without PVC matched according to the body mass index (BMI), age, sex, and calcium score. All coronary vessel segments were assessed for image quality and presence of significant stenosis.
As compared with calcium score assessment, after administration of lidocaine and during the CTCA scan PVC were completely suppressed in 22 (40%), reduced in 10 (18%), unchanged in 18 (32%), and intensified in 5 (10%) patients. Overall, there were 32 (58%) patients with sinus rhythm during CTCA as compared with only 11 (20%) patients free from PVC during calcium score assessment (p < 0.001). Image quality in 871 coronary segments including both the study group and control patients was worse in patients with PVC (p < 0.0001). However, there was no statistically significant difference in the number of patients with at least one segment of non-diagnostic quality (6% vs. 12%, p = 0.36; respectively).
Single lidocaine bolus given prior to CTCA is safe, may temporarily eliminate or reduce the intensity of arrhythmia, and hence results in improved quality of CTCA in patients with numerous PVC.
PMCID: PMC3915980  PMID: 24570719
computed tomography coronary angiography; artefacts; lidocaine
13.  Long-term outcomes of simple crossover stenting from the left main to the left anterior descending coronary artery 
Although complex bifurcation stenting in patients with non-left main (LM) bifurcation lesions has not yielded better clinical outcomes than simpler procedures, the utility of complex bifurcation stenting to treat LM bifurcation lesions has not yet been adequately explored.
In the present study, patients who underwent LM-to-left anterior descending (LAD) coronary artery simple crossover stenting to treat significant de novo distal LM or ostial LAD disease, in the absence of angiographically significant ostial left circumflex (LCX) coronary artery disease, were consecutively enrolled. The frequencies of 3-year major adverse cardiovascular events (MACEs; cardiac death, myocardial infarction, and target lesion revascularization), were analyzed.
Of 105 eligible consecutive patients, only 12 (11.4%) required additional procedures to treat ostial LCX disease after main vessel stenting. The mean percentage diameter of ostial LCX stenosis increased from 22.5% ± 15.2% to 32.3% ± 16.3% (p < 0.001) after LM-to-LAD simple crossover stenting. The 3-year incidence of MACEs was 9.7% (cardiac death 2.2%; myocardial infarction 2.2%; target lesion revascularization 8.6%), and that of stent thrombosis 1.1%. Of seven cases (7.5%) requiring restenosis, pure ostial LCX-related repeat revascularization was required by only two.
Simple crossover LM-to-LAD stenting without opening of a strut on the LCX ostium was associated with acceptable long-term clinical outcomes.
PMCID: PMC4164723  PMID: 25228835
Percutaneous coronary intervention; Coronary stenosis; Stents; Outcome
14.  Outcome from balloon induced coronary artery dissection after intracoronary β radiation 
Heart  2000;83(3):332-337.
OBJECTIVE—To evaluate the healing of balloon induced coronary artery dissection in individuals who have received β radiation treatment and to propose a new intravascular ultrasound (IVUS) dissection score to facilitate the comparison of dissection through time.
DESIGN—Retrospective study.
SETTING—Tertiary referral centre.
PATIENTS—31 patients with stable angina pectoris, enrolled in the beta energy restenosis trial (BERT-1.5), were included. After excluding those who underwent stent implantation, the evaluable population was 22 patients.
INTERVENTIONS—Balloon angioplasty and intracoronary radiation followed by quantitative coronary angiography (QCA) and IVUS. Repeat QCA and IVUS were performed at six month follow up.
MAIN OUTCOME MEASURES—QCA and IVUS evidence of healing of dissection. Dissection classification for angiography was by the National Heart Lung Blood Institute scale. IVUS proven dissection was defined as partial or complete. The following IVUS defined characteristics of dissection were described in the affected coronary segments: length, depth, arc circumference, presence of flap, and dissection score. Dissection was defined as healed when all features of dissection had resolved. The calculated dose of radiation received by the dissected area in those with healed versus non-healed dissection was also compared.
RESULTS—Angiography (type A = 5, B = 7, C = 4) and IVUS proven (partial = 12, complete = 4) dissections were seen in 16 patients following intervention. At six month follow up, six and eight unhealed dissections were seen by angiography (A = 2, B = 4) and IVUS (partial = 7, complete = 1), respectively. The mean IVUS dissection score was 5.2 (range 3-8) following the procedure, and 4.6 (range 3-7) at follow up. No correlation was found between the dose prescribed in the treated area and the presence of unhealed dissection. No change in anginal status was seen despite the presence of unhealed dissection.
CONCLUSION—β radiation appears to alter the normal healing process, resulting in unhealed dissection in certain individuals. In view of the delayed and abnormal healing observed, long term follow up is indicated given the possible late adverse effects of radiation. Although in this cohort no increase in cardiac events following coronary dissections was seen, larger populations are needed to confirm this phenomenon. Stenting of all coronary dissections may be warranted in patients scheduled for brachytherapy after balloon angioplasty.

Keywords: dissection; intravascular ultrasound; angiography; coronary artery; brachytherapy; angioplasty
PMCID: PMC1729352  PMID: 10677416
15.  Incidence of anomalous origin of coronary artery in 1879 Chinese adults on dual-source CT angiography 
Netherlands Heart Journal  2010;18(10):466-470.
Background and Objective. Dual-source CT (DSCT) has been used to detect coronary artery anomalies. The purpose of this study was to assess the incidence of anomalous origin of the coronary artery in Chinese adults.
Methods. We summarised all patients who underwent DSCT coronary angiography (CTCA) from December 2006 to February 2008, and data of anomalous origin of the coronary artery in Chinese adults were recorded.
Results. 1879 patients underwent CTCA during that period; 24 patients with an anomalous origin of the coronary artery were detected, giving an incidence of 1.3%. Fifteen patients had an anomalous origin of the right coronary artery (12 from left coronary sinus, 3 high takeoff), eight patients had an anomalous origin of the left coronary artery (LCA from posterior sinus of Valsalva in three cases, LCX from the right coronary sinus, LCX from RCA, high takeoff, LCA from right coronary sinus, and single coronary artery in one case, respectively), and one patient had an anomalous origin of both coronary arteries (high takeoff).
Conclusion. The incidence of anomalous origin of the coronary artery in Chinese adults in this study is 1.3%. DSCT can clearly visualise the anomalous origin and course of the coronary artery and is a useful screening modality. (Neth Heart J 2010;18:466–70.)
PMCID: PMC2954298  PMID: 20978590
Coronary Artery Disease; Coronary Artery Anomaly; Tomography; X-ray Computed; Angiography
16.  Directional atherectomy facilitates the interventional procedure and leads to a low rate of recurrent stenosis in left anterior descending and left circumflex artery ostium stenoses: subgroup analysis of the FLEXI‐CUT study 
Heart  2006;92(9):1285-1289.
To examine by retrospective analysis of data from the FLEXI‐CUT monocentre registry whether atherectomy can effectively simplify complex stent implantation in ostial bifurcation lesions by reducing the procedure to stenting of the left anterior descending (LAD) or left circumflex (LCX) artery ostium alone.
Patients and methods
All patients who had been enrolled in the prospective FLEXI‐CUT study (directional atherectomy with adjunctive balloon angioplasty) were retrospectively analysed on the basis of significant LAD or LCX ostial stenosis (⩾ 70% stenosis) deriving from an undiseased left main stem. The primary combined end point was the rate of target lesion revascularisation (TLR) and binary restenosis; secondary end points were procedural success and major adverse cardiac events (MACE) at the six‐month follow up.
Of 30 patients enrolled with significant LAD or LCX ostium stenosis, 29 were effectively treated with directional atherectomy (96.7% procedural success). All patients underwent single‐vessel stenting procedures of solely the LAD or LCX ostium. At follow up, binary stenosis was 25% (6 of 24), TLR (angiographic plus clinical) 10.3% (3 of 29) and total MACE 6.9% (2 of 29).
Directional atherectomy with single‐vessel stenting procedures facilitates the interventional treatment of LAD and LCX ostium stenosis, and leads to remarkably low TLR and binary stenosis at follow up.
PMCID: PMC1861141  PMID: 16449510
17.  Efficacy and Safety of the Computed Tomography Coronary Angiography Based Approach for Patients with Acute Chest Pain at an Emergency Department: One Month Clinical Follow-up Study 
Journal of Korean Medical Science  2010;25(3):466-471.
To evaluate the safety and efficacy of the computed tomography coronary angiography (CTCA) for evaluation of acute chest pain in real world population, we prospectively enrolled 296 patients with acute chest pain at emergency department (ED) from November 2005 to February 2007. The patients were grouped based on the clinical information and CTCA result. The patients with a low risk profile and no significant coronary stenosis (>50%) in CTCA were discharged immediately (Group 1, n=103). On the other hand, the patients with an intermediate risk profile without significant stenosis were observed in ED for 24 hr (Group 2, n=104). The patients with significant stenosis underwent further coronary evaluation and management accordingly (Group 3, n=89). While no false negative case was found in Group 1, seven cases (6.73%) were found in Group 2, mostly during the observation period. In Group 3, there were 54 (60.67%) cases of acute coronary syndrome including 10 myocardial infarctions. The overall accuracy of CTCA for acute coronary syndrome was 88.5% (sensitivity), 85.1% (specificity), 60.7% (positive predictive value) and 96.6% (negative predictive value). In conclusion, clinical decision based on CTCA is safe and effective for low risk patients. Further validation is needed in patients with intermediate risk profile.
PMCID: PMC2826725  PMID: 20191049
Angina; Diagnosis; Imaging; Angiography; Coronary Disease; Tomography
18.  Evaluation of coronary atheroma by 64-slice multidetector computed tomography: Comparison with intravascular ultrasound and angiography 
The Canadian Journal of Cardiology  2009;25(11):641-647.
Recent improvements in multidetector computed tomography (MDCT) with 64-slice scanners have allowed acquisition of a coronary study in 5 s to 6 s, with good temporal and spatial resolution. Previous studies have reported an underestimation of plaque burden by MDCT. Whether shorter scan times can allow correct assessment of plaque volume requires comparison with intravascular ultrasound (IVUS).
Patients (n=30) scheduled for coronary angiography also underwent MDCT and IVUS examinations within 96 h. MDCT examination was performed with a 64-slice scanner. Nitroglycerin was administered before all imaging procedures. MDCT, quantitative coronary angiography (QCA) and IVUS analyses were performed by observers blinded to other results. Plaque volumes were determined by MDCT and IVUS in one vessel, and maximum percentage diameter stenosis was identified in each coronary segment by MDCT and QCA.
The mean (± SD) plaque volume was determined to be 179.1±78.9 mm3 by MDCT and 176.1±87.9 mm3 by IVUS. There was a strong positive correlation for plaque volume between MDCT and IVUS (r=0.84, P<0.0001). Percentage diameter stenosis assessed by MDCT and QCA also correlated well (r=0.88 per patient and r=0.87 per vessel, P<0.0001 for both). The maximum percentage diameter stenosis per vessel was 38.1±30.2% with MDCT and 34.1±27.6% with QCA. The sensitivity and specificity of MDCT in detecting stenoses above 50% per vessel were 100% and 91.0%, respectively.
Plaque volumes measured by 64-slice MDCT and IVUS correlate well, without systematic underestimation. The sensitivity and specificity of MDCT to detect stenoses greater than 50% by QCA are excellent with the administration of nitroglycerin before imaging.
PMCID: PMC2776562  PMID: 19898696
Angiography; Atherosclerosis; Coronary disease; Tomography; Ultrasonics
19.  Diagnostic accuracy of dual-source CT angiography and coronary risk stratification 
The aim of this study was to evaluate the diagnostic accuracy of dual-source computed tomography (DSCT) in coronary artery disease, and to test the possibility of using this technique for coronary risk stratification.
With the advent of DSCT, it is possible to image coronary plaque noninvasively. However, the accuracy of this method in terms of sensitivity and specificity has not been determined. Furthermore, noninvasive determination of plaque composition and plaque burden may be important for improving coronary risk stratification.
Forty-six patients with known coronary artery disease underwent DSCT quantitative coronary angiography (QCA), and intravascular ultrasound (IVUS) were included in the study. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DSCT was calculated against QCA and IVUS. Plaque analysis software in a DSCT workstation was used to detect plaque characteristics associated with the Hounsfield unit (Hu) value compared with IVUS. Coronary artery plaques were classified into three types of lesions based on DSCT, and the relationship between different coronary lesions and clinical diagnosis was determined.
DSCT angiography was performed in 46 patients, and a diagnostic-quality CT image was obtained in 44 patients. Coronary angiography was performed in 138 vessels and IVUS in 102 vessels of all 46 patients. Sensitivity, specificity, PPV, and NPV of DSCT compared with QCA was 100%, 98%, 92%, and 100%, respectively. The same corresponding index of DSCT compared with IVUS was 100%, 99%, 95%, and 100%, respectively. Quantitative coronary stenosis analysis revealed a good correlation between DSCT and QCA (r = 0.85, P < 0.05, 95% confidence interval [CI] 0.60–0.87). There was also a good correlation between DSCT and IVUS (r = 0.81, P < 0.05, 95% CI 0.56–0.82). In comparison with IVUS, DSCT predicted plaque characteristics more accurately. The coefficient correlation (r) of luminal cross-sectional area and external elastic membrane cross-sectional area between DSCT and IVUS was 0.82 (P < 0.01, CI 0.67–0.89) and 0.78 (P < 0.01, CI 0.67–0.86), respectively. Three different types of plaque were identified on IVUS. Fatty plaque had a 45 ± 14 Hu value, fibrous plaque 90 ± 20, and calcified plaque 530 ± 185, respectively, on DSCT. The relationship between clinical diagnosis and coronary plaque on DSCT indicated that lesions in patients with unstable angina pectoris or ST elevation myocardial infarction were mainly discrete soft plaques, but there was no significant difference in the distributive characteristics of the lesions in patients with non-ST elevation myocardial infarction and stable angina pectoris patients.
DSCT is a noninvasive tool that allows accurate evaluation of plaque characteristics, diagnosis of coronary artery disease, and stratification of coronary risk according to different coronary plaque type.
PMCID: PMC2964946  PMID: 21057578
dual-source computed tomography; quantitative coronary angiography; intravascular ultrasound; risk stratification
20.  Relationship between breast arterial calcification on mammography with CT Calcium scoring and coronary CT angiography results 
Mammography as a non invasive method has been suggested to be helpful in predicting coronary artery disease. This study aimed to investigate whether presence and severity of breast artery calcification (BAC) on mammograms is associated with computed tomography coronary angiography (CTCA) finding such as coronary artery calcium (CAC) score and the severity of coronary artery stenosis.
Materials and Methods:
This cross-sectional study was performed on 150 women aged >40 years who were referred for CTCA. Women who had undergone screening mammography during the first year after CTCA entered the study. CAC score was determined and the severity of coronary artery stenosis was classified into normal, non-significant stenosis, or significant stenosis. Based on the severity of BAC, patients were also grouped into normal, mild, moderate, or severe groups. Then, the correlation between BAC severity and CAC score was determined. Patients with different BAC severity were also compared regarding the relative frequency of different grades of coronary artery stenosis.
Mean age of subjects with BAC (n: 35) was significantly higher than patients without BAC (n: 115) (68.03 ± 6.16 versus 54.36 ± 7.63 years, P < 0.0001). Although the relative frequency of different grades of coronary artery stenosis was significantly higher in women with BAC (P < 0.0001), after controlling for age, there was no significant difference between patients with different severity of BAC in the mean of CAC score (P: 0.09). In addition, the correlation between BAC severity and CAC score was not statistically significant (R: 0.09, P: 0.26).
We concluded that presence and severity of BAC have no significant correlation with CAC score on CTCA.
PMCID: PMC3988590  PMID: 24761387
Breast arterial calcification; calcium scoring; coronary CT Angiography; mammography
21.  Angiographically borderline left main coronary artery lesions: correlation of transthoracic doppler echocardiography and intravascular ultrasound: a pilot study 
the clinical decision making could be difficult in patients with borderline lesions (visually assessed stenosis severity of 30 to 50%) of the left main coronary artery (LM). The aim of the study was to evaluate the relationship between transthoracic Doppler (TTDE) peak diastolic flow velocity (PDV) and intravascular ultrasound (IVUS) measurements in the assessment of angiographically borderline LM lesions.
27 patients (mean age 64 ± 8 years, 21 males) with borderline LM stenosis referred for IVUS examination were included in the study. We performed standard IVUS with minimal lumen area (MLA) and plaque burden (PB) measurement and routine quantitative coronary angiography (QCA) with diameter stenosis (%DS) and area stenosis (%AS) assessment in all. During TTDE, resting PDV was measured in the LM.
interpretable Doppler signal could be obtained in 24 patients (88% feasibility); therefore these patients entered the final analysis. MLA was 7.1 ± 2.7 mm2. TTDE measured PDV correlated significantly with IVUS-derived MLA (r = -0.46, p < 0.05) and plaque burden (r = 0.51, p < 0.05). Using a velocity cut-off of 112 cm/sec TTDE showed a 92% sensitivity and 62% specificity to identify IVUS-significant (MLA < 6 mm2) LM stenosis.
In angiographically borderline LM disease, resting PDV from transthoracic echocardiography is increased in presence of increased plaque burden by IVUS. TTDE evaluation might be a useful adjunct to other invasive and non-invasive methods in the assessment of borderline LM lesions. Further, large scale studies are needed to establish the exact cut-off value of PDV for routine clinical application.
PMCID: PMC3129577  PMID: 21672192
22.  Safety and efficacy of intravenous esmolol before prospective electrocardiogram-triggered high-pitch spiral acquisition for computed tomography coronary angiography 
In order to acquire a high quality image with a low radiation dose, prospective electrocardiogram (ECG)-triggered computed tomography coronary angiography (CTCA) requires a stable heart rate (HR) < 65 beats/min. Esmolol has the advantage of reducing HR. The objective of this article is to assess the value of intravenous esmolol treatment before prospective ECG-triggered high-pitch spiral acquisition for CTCA.
From March 2013 to June 2013, 313 patients underwent prospective ECG-triggered CTCA. Two hundred and thirty two of them received esmolol before angiography. We retrospectively analyzed clinical characteristics, esmolol dose, radiation exposure dose, and the change in HR and blood pressure in these 232 patients.
A total of 232 patients with a HR > 65 beats/min before CTCA examination received intravenous esmolol treatment (mean dose of 57.26 ± 15.39 mg). The mean initial HR (HR1), slowest HR (HR2), and the HR 30 min after HR2 (HR3) were 75.06 ± 5.59, 60.75 ± 4.00, and 75.54 ± 5.96 beats/min, respectively (HR1 vs. HR2, P < 0.0001; HR1 vs. HR3, P = 0.377). The mean time from esmolol administration to HR2 was 24.25 ± 4.97 s and the mean effective radiation dose was 2.28 ± 0.02 mSv.
HR could be rapidly controlled at an optimum level with intravenous esmolol before prospective ECG-triggered high-pitch spiral acquisition for CTCA. Consequently, the patients received a very low radiation dose.
PMCID: PMC3981982  PMID: 24748880
Esmolol; Electrocardiogram; Coronary angiography; Heart rate
23.  Comparative Analysis between SPECT Myocardial Perfusion Imaging and CT Coronary Angiography for Diagnosis of Coronary Artery Disease 
The study aims to discuss the relationship and difference between myocardial perfusion imaging (MPI) using SPECT and CT coronary angiography (CTCA) for diagnosis of coronary artery disease (CAD). Five hundred and four cases undergoing MPI and CTCA were comparatively analyzed, including fifty six patients undergoing invasive coronary angiography in the same period. Among patients with negative MPI results, negative or positive CTCA occupied 84.7% or 15.3%, respectively. Among patients with positive MPI, positive or negative CTCA occupied 67.2% or 32.8%, respectively. Among patients with negative CTCA, negative or positive MPI occupied 94.4% or 5.6%, respectively. Among patients with positive CTCA, positive or negative MPI occupied 40.2% or 59.8%, respectively. Negative predictive value was relatively higher than the positive predictive value for positive CTCA eliminating or predicting abnormal haemodynamics. And there was no significant difference for sensitivity, specificity, and accuracy of MPI or CTCA in diagnosing CAD. Both MPI and CTCA have good diagnostic performance for CAD. They provide different and complementary information for diagnosis and evaluation of CAD, namely, detection of ischemia versus detection of atherosclerosis, which are quite different but have a definite internal link for each other.
PMCID: PMC3405566  PMID: 22848809
24.  Prevalence of coronary artery ectasia in older adults and the relationship with epicardial fat volume by cardiac computed tomography angiography 
Coronary artery ectasia (CAE) refers to abnormal dilation of coronary artery segments to 1.5 times of adjacent normal ones. Epicardial fat is associated with cardiovascular risk factors. The relationship between CAE and epicardial fat has not yet been investigated. This study aimed to assess the relationship between CAE and epicardial fat volume (EFV) in older people by dual-source computed tomography coronary angiography (CTCA).
We prospectively enrolled 1400 older adults who were scheduled for dual-source CTCA. Under reconstruction protocols, patients with abnormal segments 1.5 times larger than the adjacent segments were accepted as CAE. EFV was measured by semi-automated software. Traditional risk factors in CAE patients, as well as the extent of EFV, were analyzed and compared to non-CAE group.
A total of 885 male and 515 female older patients were enrolled. CAE was identified by univariable analysis in 131 patients and significantly correlated to hypertension, smoking, hyperlipidemia, prior percutaneous coronary intervention and ascending aorta aneurysm. EFV was shown to be significantly higher in CAE patients than patients without ectasia. In multivariable analyses, EFV (P = 0.018), hypertension (P < 0.001) and hyperlipidemia (P < 0.001) were significantly correlated to CAE. There was a significant negative correlation between EFV and Markis classification.
CAE can be reliably recognized by dual-source CTCA. Epicardial fat might play a role in etiopathogenesis and progression of CAE, providing a new target for treating ectasia.
PMCID: PMC3627703  PMID: 23610568
Coronary artery ectasia; Epicardial fat; Cardiac computed tomography angiography
25.  Does a well developed collateral circulation predispose to restenosis after percutaneous coronary intervention? An intravascular ultrasound study 
Heart  2005;92(6):763-767.
To evaluate whether a well developed collateral circulation predisposes to restenosis after percutaneous coronary intervention (PCI).
Prospective observational study.
Patients and setting
58 patients undergoing elective single vessel PCI in a tertiary referral interventional cardiac unit in the UK.
Collateral flow index (CFI) was calculated as (Pw − Pv)/(Pa − Pv), where Pa, Pw, and Pv are aortic, coronary wedge, and right atrial pressures during maximum hyperaemia. Collateral supply was considered poor (CFI < 0.25) or good (CFI ⩾ 0.25).
Main outcome measures
In‐stent restenosis six months after PCI, classified as neointimal volume ⩾ 25% stent volume on intravascular ultrasound (IVUS), or minimum lumen area ⩽ 50% stent area on IVUS, or minimum lumen diameter ⩽ 50% reference vessel diameter on quantitative coronary angiography.
Patients with good collaterals had more severe coronary stenoses at baseline (90 (11)% v 75 (16)%, p < 0.001). Restenosis rates were similar in poor and good collateral groups (35% v 43%, p  =  0.76 for diameter restenosis, 27% v 45%, p  =  0.34 for area restenosis, and 23% v 24%, p  =  0.84 for volumetric restenosis). CFI was not correlated with diameter, area, or volumetric restenosis (r2 < 0.1 for each). By multivariate analysis, stent diameter, stent length, > 10% residual stenosis, and smoking history were predictive of restenosis.
A well developed collateral circulation does not predict an increased risk of restenosis after PCI.
PMCID: PMC1860667  PMID: 16216859
collateral flow index; intravascular ultrasound; restenosis; percutaneous coronary intervention

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