Imran Arif

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.

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.

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 myocardial contractility on hemodynamic end points under concomitant microvascular disease in a porcine model

In this study, coronary diagnostic parameters, pressure drop coefficient (CDP: ratio of trans-stenotic pressure drop to distal dynamic pressure), and lesion flow coefficient (LFC: ratio of % area stenosis (%AS) to the CDP at throat region), were evaluated to distinguish levels of %AS under varying contractility conditions, in the presence of microvascular disease (MVD). In 10 pigs, %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop, left ventricular pressure (p), and velocity were obtained. Contractility was calculated as (dp/dt)max, categorized into low contractility <900 mmHg/s and high contractility >900 mmHg/s, and in each group, compared between %AS <50 and >50 using analysis of variance. In the presence of MVD, between the %AS <50 and >50 groups, values of CDP (71 ± 1.4 and 121 ± 1.3) and LFC (0.10 ± 0.04 and 0.19 ± 0.04) were significantly different (P < 0.05), under low-contractility conditions. A similar %AS trend was observed under high-contractility conditions (CDP: 18 ± 1.4 and 91 ± 1.4; LFC: 0.08 ± 0.04 and 0.25 ± 0.04). Under MVD conditions, similar to fractional flow reserve, CDP and LFC were not influenced by contractility.

Evaluation of lesion flow coefficient for the detection of coronary artery disease in patient groups from two academic medical centers

BACKGROUND In this study, lesion flow coefficient (LFC: ratio of % area stenosis [%AS] to the square root of the ratio of the pressure drop across the stenosis to the dynamic pressure in the throat region), that combines both the anatomical (%AS) and functional measurements (pressure and flow), was assessed for application in a clinical setting. METHODS AND RESULTS Pressure, flow, and anatomical values were obtained from patients in 251 vessels from two different centers. Fractional flow reserve (FFR), Coronary flow reserve (CFR), hyperemic stenosis resistance index (HSR) and hyperemic microvascular index (HMR) were calculated. Anatomical data was corrected for the presence of guidewire and the LFC values were calculated. LFC was correlated with FFR, CFR, HSR, HMR, individually and in combination with %AS. The p<0.05 was used for statistical significance. LFC correlated significantly when the FFR (pressure-based), CFR (flow-based), and anatomical measure %AS were combined (r=0.64; p<0.05). Similarly, LFC correlated significantly when HSR, HMR, and %AS were combined (r=0.72; p<0.05). LFC was able to significantly (p<0.05) distinguish between the two concordant and the two discordant groups of FFR and CFR, corresponding to the clinically used cut-off values (FFR=0.80 and CFR=2.0). The LFC could also significantly (p<0.05) distinguish between the normal and abnormal microvasculature conditions in the presence of non-significant epicardial stenosis, while the comparison was borderline significant (p=0.09) in the presence of significant stenosis. CONCLUSION LFC, a parameter that combines both the anatomical and functional end-points, has the potential for application in a clinical setting for CAD evaluation.

Benefit of ECG-gated rest and stress N-13 cardiac PET imaging for quantification of LVEF in ischemic patients.

BackgroundECG-gated rest–stress cardiac PET can lead to simultaneous quantification of both left ventricular ejection fraction and flow impairment. In this study, our aim was to assess the benefit of rest and stress PET ejection fraction (EF) (EFp) in relation to single-photon emission computed tomography (SPECT) EF (EFs) and echocardiography EF (EFe). To this effect, the EFp was compared with EFs and EFe. Further, the relation between rest and stress EFp was also assessed. MethodsECG-gated N-13 ammonia rest and stress PET imaging was performed in 26 patients. EFp values were obtained using gated reconstruction of the data in Flowquant. In 13 patients, EFs and EFe values were obtained through chart review. Correlation, analysis of variance, and Bland–Altman analyses were performed. P values less than 0.05 were used for statistical significance. ResultsThe rest and stress EFp values correlated significantly (r=0.80 and 0.71, respectively; P<0.05) with EFs values. There was moderate correlation with statistical significance (P<0.05) between the rest and stress EFp and EFe values (r=0.58 and 0.50, respectively). The mean rest and stress EFp values were not significantly different from mean EFs values. Also, the rest EFp and stress EFp values correlated well (r=0.81, P<0.05) and were not significantly different. Bland–Altman analysis showed no significant bias between the rest and stress EFp, and EFs, and EFe values. ConclusionRest and stress EFp values obtained through an ECG-gated PET scan can be used for clinical diagnosis in place of conventional methods like SPECT and echocardiography.

Non-invasive assessment of the severity of aortic stenosis by Doppler derived aortic valve coefficient: a retrospective feasibility study in humans.

Background: Accurate assessment of the severity of stenosis is critical in patients with aortic stenosis. The ambiguities and imprecisions of the current diagnostic parameters can result in suboptimal clinical decisions. In this feasibility study, we investigate the functional diagnostic parameter AVC (Aortic Valve coefficient: ratio of the total transvalvular pressure drop to the proximal dynamic pressure) in the non-invasive assessment of the severity of aortic stenosis by correlating with the current diagnostic parameters. Original Research Article Paul et al.; BJMMR, 8(2): 177-191, 2015; Article no.BJMMR.2015.438 178 Methods and Results: AVC was calculated using Doppler measured diagnostic parameters obtained from retrospective chart reviews. A theoretical pressure recovery correction was applied to the pressure drop calculated from Doppler measurements to obtain AVC. A statistically significant and strong combined linear correlation (r = 0.93, p<0.001) of AVC with the transvalvular pressure drop and the left ventricular outflow tract velocity was observed. The mean values of AVC were shown to better delineate moderate and severe stenosis (54% difference) than the mean values of Doppler measured pressure drop and aortic valve area (22% and 25% difference, respectively), when the patients were categorized based on the catheterization measured pressure drop. Conclusion: The feasibility of using pressure and flow measurements obtained from Doppler measurements in a single combined diagnostic index for the assessment of aortic stenosis severity has been evaluated. The nondimensional clinical parameter, AVC, is expected to account for the variation in flow and pressure drop and thus improve the delineation of different grades of aortic stenosis. AVC must be further evaluated in a controlled prospective study.

Congenital Anastomosis Between Left Anterior Mammary and Pulmonary Vasculatures

Abstract:Several case reports have described the presence of acquired fistula connecting the left internal mammary artery to the pulmonary vasculature; however, occurrence of this type of congenital fistulas is less common. The authors present a case of a congenital left internal mammary artery-pulmonary vasculature fistula that was incidentally found during a coronary angiography in a patient who was being evaluated for coronary artery bypass surgery. The particulars of the case are discussed, and the literature is reviewed.

Drug-eluting stents for saphenous vein graft lesions.

Wiisanen et al. ([1][1]) performed a meta-analysis of 23 studies comparing drug-eluting stents (DES) with bare-metal stents for saphenous vein graft lesions, and they demonstrated the superiority of DES in reducing death, myocardial infarction, and target vessel revascularization. Eleven meta-