Tarek Helmy

Safety and efficacy of drug eluting stents compared with bare metal stents for saphenous vein graft interventions: A comprehensive meta-analysis of randomized trials and observational studies comprising 7,994 patients†

Background: Saphenous vein graft (SVG) lesions remain amongst the most challenging lesions for percutaneous coronary intervention (PCI). It is unknown whether drug eluting stents (DES) are superior to bare metal stents (BMS) for such lesions. Our objective is to determine the safety and efficacy of DES compared with BMS for SVG lesions by performing a meta‐analysis of clinical trials and observational studies. Data Sources: PubMed, Cochrane Register of Controlled Trials, conference proceedings, and internet‐based resources of clinical trials. Study Selection:Studies comparing DES vs. BMS for SVG lesions with at least > 30 patients in each study reporting the outcomes of interest [death, myocardial infarction (MI), target vessel revascularization (TVR), stent thrombosis (ST), and the composite of death, TVR and MI (major adverse cardiac events; MACE)] with at least 6 months clinical follow‐up. The primary outcome of interest was death. Results:Two randomized trials, one subgroup analysis of a randomized trial and 26 observational studies comprising a total of 7,994 patients (4,187 patients in DES and 3,807 patients in BMS group) were included in the analysis .Mean follow‐up duration was 21 ± 11 months (6–48 months). In the overall population, MACE events were 19% in DES and 28% in BMS with a risk ratio (RR) of 0.7 (0.6, 0.8) P < 0.00001. This effect of MACE was sustained in studies with >2 years follow‐up with RR of 0.77 (0.65, 0.91) P = 0.003. Death rate was 7.8% in DES and 9% in BMS with a RR of 0.82 (0.7, 0.97) P = 0.02. MI rate was 5.7% in DES and 7.6% in BMS with RR of 0.72 (0.57, 0.91) P = 0.007. TVR was 12% in DES and 17% in BMS with RR of 0.71 (0.59, 0.85) P = 0.0002. ST was 1% in DES and 1.7 % in BMS RR of 0.61 (0.35, 1.06) P = 0.08. Specifically in randomized controlled trials, DES were associated with no significant differences in overall mortality [RR = 1.97; 95% confidence interval (CI), 0.17–23; P = 0.58] or MI (RR = 1.24; 95% CI, 0.3–5.5; P = 0.78) compared with BMS. Conclusions:Based on the results of this meta‐analysis, DES may be considered as a safe and efficacious option for the percutaneous intervention of SVG lesions.

Hemodynamic diagnostics of epicardial coronary stenoses: in-vitro experimental and computational study

BackgroundThe severity of epicardial coronary stenosis can be assessed by invasive measurements of trans-stenotic pressure drop and flow. A pressure or flow sensor-tipped guidewire inserted across the coronary stenosis causes an overestimation in true trans-stenotic pressure drop and reduction in coronary flow. This may mask the true severity of coronary stenosis. In order to unmask the true severity of epicardial stenosis, we evaluate a diagnostic parameter, which is obtained from fundamental fluid dynamics principles. This experimental and numerical study focuses on the characterization of the diagnostic parameter, pressure drop coefficient, and also evaluates the pressure recovery downstream of stenoses.MethodsThree models of coronary stenosis namely, moderate, intermediate and severe stenosis, were manufactured and tested in the in-vitro set-up simulating the epicardial coronary network. The trans-stenotic pressure drop and flow distal to stenosis models were measured by non-invasive method, using external pressure and flow sensors, and by invasive method, following guidewire insertion across the stenosis. The viscous and momentum-change components of the pressure drop for various flow rates were evaluated from quadratic relation between pressure drop and flow. Finally, the pressure drop coefficient (CDPe) was calculated as the ratio of pressure drop and distal dynamic pressure. The pressure recovery factor (η) was calculated as the ratio of pressure recovery coefficient and the area blockage.ResultsThe mean pressure drop-flow characteristics before and during guidewire insertion indicated that increasing stenosis causes a shift in dominance from viscous pressure to momentum forces. However, for intermediate (~80%) area stenosis, which is between moderate (~65%) and severe (~90%) area stenoses, both losses were similar in magnitude. Therefore, guidewire insertion plays a critical role in evaluating the hemodynamic severity of coronary stenosis. More importantly, mean CDPe increased (17 ± 3.3 to 287 ± 52, n = 3, p < 0.01) and mean η decreased (0.54 ± 0.04 to 0.37 ± 0.05, p < 0.01) from moderate to severe stenosis during guidewire insertion.ConclusionThe wide range of CDPe is not affected that much by the presence of guidewire. CDPe can be used in clinical practice to evaluate the true severity of coronary stenosis due to its significant difference between values measured at moderate and severe stenoses.

Development of Appropriate Coronary Heart Disease Risk Prediction Models in HIV-Infected Patients

Prediction equations for coronary heart disease (CHD) risk are useful tools that inform clinicians and patients about the absolute risk for developing CHD. A basic principle in CHD prevention is that the intensity of risk-reducing interventions should be based on the individual patient’s absolute CHD risk. In the current era of human immunodeficiency virus (HIV) infection and highly active antiretroviral therapy (HAART), knowing one’s CHD risk and acting to reduce it have become imperative to long-term survival. Given the increased life expectancy as a result of HAART, more HIV-infected persons will experience complications not related to HIV per se and will reach an age at which they are at increased risk for developing CHD. However, existing CHD risk prediction equations were not developed in HIV-infected adults or children. In the general population, CHD risk prediction models derived from the Framingham Heart Study estimate the risk of total CHD (angina pectoris, myocardial infarction [MI], CHD death)1 or estimate the risk for hard CHD end points (MI, CHD).2 The traditional risk factors used to predict CHD risk and how risk factor alterations affect CHD outcomes in HIV-infected and HIV-seronegative people are summarized in the Table. The estimates of the relative effects of traditional risk factors on CHD outcomes appear similar between HIV- and non–HIV-infected patients. However, they are based on only 2 studies in HIV-infected patients. Although traditional CHD risk factors may operate in the same manner in HIV patients as in the general population, there may still be a need to identify and evaluate HIV-specific CHD risk factors and equations, to refine existing CHD prediction equations, and to develop new HIV-specific CHD prediction equations for adults, adolescents, and children. To date, Framingham CHD risk predictions have performed reasonably well when applied to HIV-infected patients. We need to evaluate …

Health Status After Treatment for Coronary Artery Disease and Type 2 Diabetes Mellitus in the Bypass Angioplasty Revascularization Investigation 2 Diabetes Trial

Background Health status is a key outcome for comparing treatments, particularly when mortality does not differ significantly.Background— Health status is a key outcome for comparing treatments, particularly when mortality does not differ significantly. Methods and Results— Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) randomized 2368 patients with type 2 diabetes mellitus and stable ischemic heart disease to (1) prompt revascularization versus medical therapy and (2) insulin sensitization versus insulin provision. Randomization was stratified by the intended method of revascularization, coronary artery bypass graft surgery or percutaneous coronary intervention. The Duke Activity Status Index and RAND Energy, Health Distress, and Self-Rated Health scales were assessed at study entry and annually thereafter; linear mixed models were used to evaluate the effect of randomized treatment on these measures. Health status improved significantly from baseline to 1 year (P<0.001) in each randomized treatment group. Compared with medical therapy, prompt revascularization was associated with significantly greater improvements in Duke Activity Status Index (1.32 points; P<0.001), Energy (1.36 points; P=0.02), and Self-rated Health (1.77 points; P=0.007) but not Health Distress (−0.47; P=0.46). These treatment effects were largely maintained over 4 years of follow-up. The effect of revascularization on the Duke Activity Status Index was significantly larger in the subgroup of patients intended for coronary artery bypass graft surgery compared with the subgroup intended for percutaneous coronary intervention. Health status did not differ significantly on any of the 4 measures between the insulin provision and insulin sensitization strategies. Conclusions— Prompt coronary revascularization was associated with small yet statistically significant improvements in health status compared with initial medical therapy among patients with diabetes mellitus and stable ischemic heart disease. Clinical Trial Registration— http://www.clinicaltrials.gov. Unique identifier: NCT00006305.

Impact of kissing balloon inflation on the main vessel stent volume, area, and symmetry after side-branch dilation in patients with coronary bifurcation lesions: a serial volumetric intravascular ultrasound study.

OBJECTIVES Intravascular ultrasound (IVUS) was performed to investigate the impact of kissing balloon inflation (KBI) on the main vessel (MV) stent volume, area, and symmetry after side-branch (SB) dilation in patients with coronary bifurcation lesions (CBL). BACKGROUND It remains controversial whether KBI would restore the MV stent area and symmetry loss after SB dilation. METHODS A total of 88 serial IVUS examinations of the MV were performed after MV angioplasty, MV stenting, SB dilation, and KBI in 22 patients with CBL. The MV stent was divided into proximal, bifurcation, and distal segments; the stent volume index (SVI), minimal stent area (MSA), stent symmetry index (SSI), and external elastic membrane (EEM) volume index were measured in 198 stent segments and compared after MV stenting, SB dilation, and KBI. RESULTS In the bifurcation segment, SVI, MSA, and SSI were significantly smaller after SB dilation than after MV stenting and KBI (SVI was 6.10 ± 1.50 mm(3)/mm vs. 6.68 ± 1.60 mm(3)/mm and 6.57 ± 1.60 mm(3)/mm, respectively, p < 0.05; MSA was 5.15 ± 1.30 mm(2) vs. 6.08 ± 1.40 mm(2) and 5.86 ± 1.50 mm(2), respectively, p < 0.05; and SSI was 0.78 ± 0.02 mm(2) vs. 0.87 ± 0.03 mm(2) and 0.84 ± 0.03 mm(2), respectively, p < 0.05). KBI restored the MV SVI, MSA, and SSI after SB dilation. In the proximal segment, SVI, MSA, and EEM volume index were significantly larger, but SSI was smaller after KBI than after MV stenting and SB dilation. In the distal segment, neither SB dilation nor KBI had a significant impact on the MV stent volume or symmetry. CONCLUSIONS This is the first comprehensive volumetric IVUS analysis of CBL, to our knowledge, demonstrating that KBI restores the MV stent volume, area, and symmetry loss after SB dilation in the bifurcation segment, and induces asymmetric stent expansion in the proximal segment.

Influence of heart rate on fractional flow reserve, pressure drop coefficient, and lesion flow coefficient for epicardial coronary stenosis in a porcine model

A limitation in the use of invasive coronary diagnostic indexes is that fluctuations in hemodynamic factors such as heart rate (HR), blood pressure, and contractility may alter resting or hyperemic flow measurements and may introduce uncertainties in the interpretation of these indexes. In this study, we focused on the effect of fluctuations in HR and area stenosis (AS) on diagnostic indexes. We hypothesized that the pressure drop coefficient (CDP(e), ratio of transstenotic pressure drop and distal dynamic pressure), lesion flow coefficient (LFC, square root of ratio of limiting value CDP and CDP at site of stenosis) derived from fluid dynamics principles, and fractional flow reserve (FFR, ratio of average distal and proximal pressures) are independent of HR and can significantly differentiate between the severity of stenosis. Cardiac catheterization was performed on 11 Yorkshire pigs. Simultaneous measurements of distal coronary arterial pressure and flow were performed using a dual sensor-tipped guidewire for HR < 120 and HR > 120 beats/min, in the presence of epicardial coronary lesions of <50% AS and >50% AS. The mean values of FFR, CDP(e), and LFC were significantly different (P < 0.05) for lesions of <50% AS and >50% AS (0.88 ± 0.04, 0.76 ± 0.04; 62 ± 30, 151 ± 35, and 0.10 ± 0.02 and 0.16 ± 0.01, respectively). The mean values of FFR and CDP(e) were not significantly different (P > 0.05) for variable HR conditions of HR < 120 and HR > 120 beats/min (FFR, 0.81 ± 0.04 and 0.82 ± 0.04; and CDP(e), 95 ± 33 and 118 ± 36). The mean values of LFC do somewhat vary with HR (0.14 ± 0.01 and 0.12 ± 0.02). In conclusion, fluctuations in HR have no significant influence on the measured values of CDP(e) and FFR but have a marginal influence on the measured values of LFC. However, all three parameters can significantly differentiate between stenosis severities. These results suggest that the diagnostic parameters can be potentially used in a better assessment of coronary stenosis severity under a clinical setting.

Spontaneous left main coronary artery dissection complicated by pseudoaneurysm formation in pregnancy: role of CT coronary angiography

We report a case of a 26-year-old female, who presented at 34 weeks of an uncomplicated pregnancy with an acute ST elevation anterior wall myocardial infarction. Cardiac catheterization suggested a left main coronary artery dissection with pseudoaneurysm formation. The patients course was complicated by congestive heart failure. She was initially managed conservatively by a multidisciplinary team including heart failure specialists, obstetricians, and cardiovascular surgeons. 4 days after admission, her LMC was imaged by dual-source 64 slice Cardiac computed tomography, coronary dissection was identified extending to the lumen, and the presence of pseudoaneurysm was confirmed. She underwent subsequently a staged procedure, which included placement of an intra-aortic balloon pump, cesarean section, and coronary artery bypass grafting. This case illustrates the utility of coronary artery CT imaging to assess the complexity and stability of coronary artery dissections, thereby helping to determine the need for, and timing of revascularization procedures.

Racial Differences in the Association Between Self-Rated Health Status and Objective Clinical Measures Among Participants in the BARI 2D Trial

OBJECTIVES We explored whether and how race shapes perceived health status in patients with type 2 diabetes mellitus and coronary artery disease. METHODS We analyzed self-rated health (fair or poor versus good, very good, or excellent) and associated clinical risk factors among 866 White and 333 Black participants in the Bypass Angioplasty Revascularization Investigation 2 Diabetes trial. RESULTS Michigan Neuropathy Screening Instrument scores, regular exercise, and employment were associated with higher self-rated health (P < .05). Blacks were more likely than were Whites to rate their health as fair or poor (adjusted odds ratio [OR] = 1.88; 95% confidence interval [CI] = 1.38, 2.57; P < .001). Among Whites but not Blacks, a clinical history of myocardial infarction (OR = 1.61; 95% CI = 1.12, 2.31; P < .001) and insulin use (OR = 1.62; 95% CI = 1.10, 2.38; P = .01) was associated with a fair or poor rating. A post-high school education was related to poorer self-rated health among Blacks (OR = 1.86; 95% CI = 1.07, 3.24; P < .001). CONCLUSIONS Symptomatic clinical factors played a proportionally larger role in self-assessment of health among Whites with diabetes and coronary artery disease than among Blacks with the same conditions.

Functional diagnosis of coronary stenoses using pressure drop coefficient: a pilot study in humans.

Myocardial fractional flow reserve (FFR) in conjunction with coronary flow reserve (CFR) is used to evaluate the hemodynamic severity of coronary lesions. However, discordant results between FFR and CFR have been observed in intermediate coronary lesions. A functional parameter, pressure drop coefficient (CDP; ratio of pressure drop to distal dynamic pressure), was assessed using intracoronary pressure drop (dp) and average peak velocity (APV). The CDP is a nondimensional ratio, derived from fundamental fluid dynamic principles. We sought to evaluate the correlation of CDP with FFR, CFR, and hyperemic stenosis resistance (HSR: ratio of pressure drop to APV) in human subjects.

Effect of heart rate on hemodynamic endpoints under concomitant microvascular disease in a porcine model

Diagnosis of the ischemic power of epicardial stenosis with concomitant microvascular disease (MVD) is challenging during coronary interventions, especially under variable hemodynamic factors like heart rate (HR). The goal of this study is to assess the influence of variable HR and percent area stenosis (%AS) in the presence of MVD on pressure drop coefficient (CDP; ratio of transstenotic pressure drop to the distal dynamic pressure) and lesion flow coefficient (LFC; ratio of %AS to the CDP at the throat region). We hypothesize that CDP and LFC are independent of HR. %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop (DP) and velocity were done in 11 Yorkshire pigs. Fractional flow reserve (FFR), CDP, and LFC were calculated for the groups HR < 120 and HR > 120 beats/min, %AS < 50 and %AS > 50, and additionally for DP < 14 and DP > 14 mmHg, and analyzed using regression and ANOVA analysis. Regression analysis showed independence between HR and the FFR, CDP, and LFC while it showed dependence between %AS and the FFR, CDP, and LFC. In the ANOVA analysis, for the HR < 120 beats/min and HR > 120 beats/min groups, the values of FFR (0.82 ± 0.02 and 0.82 ± 0.02), CDP (83.15 ± 26.19 and 98.62 ± 26.04), and LFC (0.16 ± 0.03 and 0.15 ± 0.03) were not significantly different (P > 0.05). However, for %AS < 50 and %AS > 50, the FFR (0.89 ± 0.02 and 0.75 ± 0.02), CDP (35.97 ± 25.79.10 and 143.80 ± 25.41), and LFC (0.09 ± 0.03 and 0.22 ± 0.03) were significantly different (P < 0.05). A similar trend was observed between the DP groups. Under MVD conditions, FFR, CDP, and LFC were not significantly influenced by changes in HR, while they can significantly distinguish %AS and DP groups.