Markers of coronary plaque vulnerability, such as a high lipid burden, increased inflammatory activity, and a thin fibrous cap, have been identified in histological studies. In vivo, grayscale ...intravascular ultrasound (IVUS) provides more in-depth information on coronary artery plaque burden than conventional angiography but is unable to accurately distinguish between noncalcific tissue types within the plaque. An analysis of IVUS radiofrequency backscatter based on spectral pattern recognition, such as virtual histology IVUS, allows detailed scrutiny of plaque composition and classification of coronary lesions. This review discusses the virtual histology IVUS technology and its accuracy in identifying vulnerable plaque features, focusing on its use in predicting patient outcomes after acute coronary syndrome, and its limitations in clinical practice.
Bioresorbable vascular scaffolds (BVS) present different mechanical properties as compared to metallic platform stents. Therefore, the standard procedural technique to achieve appropriate deployment ...may differ.
Fifty-two lesions treated with a 3 x 18 mm BVS were imaged with optical coherence tomography (OCT) post-implantation and screened for parameters suggesting non-optimal deployment. These included minimal scaffold area (minSA)<5 mm², residual area stenosis (RAS)>20%, edge dissections, incomplete scaffold/strut apposition (ISA)>5% and scaffold pattern irregularities. The angiographic proximal and distal maximal lumen diameters (DMAX) were measured by quantitative coronary angiography. Based on the DMAX values, the population was divided into three groups: DMAX <2.5 mm (n=13), DMAX between 2.5-3.3 mm (n=30) and DMAX >3.3 mm (n=9). All three groups presented with similar pre-implantation angiographic characteristics except for the vessel size and were treated with similar balloon/artery ratios. The group with a DMAX <2.5 mm presented with a higher percentage of lesions with minSA <5 mm² (30.8% vs. 10.0% vs. 0%; p=0.08) and edge dissections (61.5% vs. 33.3% vs. 11.1%; p=0.05). Lesions with >5% of ISA were significantly higher in the group with DMAX >3.3 mm (7.7% vs. 36.7% vs. 66.7%; p=0.02). RAS >20% was similar between all groups (46.2 vs. 53.3 vs. 77.8%; p=0.47) and scaffold pattern irregularities were only documented in three cases.
BVS implantation guided with quantitative angiography may improve the OCT findings of optimal deployment. The clinical significance of these angiographic and OCT findings warranted long term follow-up of larger cohort of patients.
The purpose of this study was to assess the impact of body mass index (BMI) on clinical outcome of patients treated by percutaneous coronary intervention (PCI) using drug-eluting stents. Patients ...were stratified according to BMI as normal (<25 kg/m2 ), overweight (25 to 30 kg/m2 ), or obese (>30 kg/m2 ). At 5-year follow-up all-cause death, myocardial infarction, clinically justified target vessel revascularization (TVR), and definite stent thrombosis were assessed. A complete dataset was available in 7,427 patients, of which 45%, 22%, and 33% were classified according to BMI as overweight, obese, and normal, respectively. Mean age of patients was significantly older in those with a normal BMI (p <0.05). Incidence of diabetes mellitus, hypertension, and dyslipidemia increased as BMI increased (p <0.05). Significantly higher rates of TVR (15.3% vs 12.8%, p = 0.02) and early stent thrombosis (1.5% vs 0.9%, p = 0.04) were observed in the obese compared to the normal BMI group. No significant difference among the 3 BMI groups was observed for the composite of death/myocardial infarction/TVR or for definite stent thrombosis at 5 years, whereas the normal BMI group was at higher risk for all-cause death at 5 years (obese vs normal BMI, hazard ratio 0.74, confidence interval 0.53 to 0.99, p = 0.05; overweight vs normal BMI, hazard ratio 0.73, confidence interval 0.59 to 0.94, p = 0.01) in the multivariate Cox proportional hazard model. Age resulted in a linearly dependent covariate with BMI in the all-cause 5-year mortality multivariate model (p = 0.001). In conclusion, the “obesity paradox” observed in 5-year all-cause mortality could be explained by the higher rate of elderly patients in the normal BMI group and the existence of colinearity between BMI and age. However, obese patients had a higher rate of TVR and early stent thrombosis and a higher rate of other risk factors such as diabetes mellitus, hypertension, and hypercholesterolemia.
The bioresorbable vascular stent (BVS) is totally translucent and radiolucent, leading to challenges when using conventional invasive imaging modalities. Agreement between quantitative coronary ...angiography (QCA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) in the BVS is unknown. Forty five patients enrolled in the ABSORB cohort B1 study underwent coronary angiography, IVUS and OCT immediately post BVS implantation, and at 6 months. OCT estimated stent length accurately compared to nominal length (95% CI of the difference: −0.19; 0.37 and −0.15; 0.47 mm
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for baseline and 6 months, respectively), whereas QCA incurred consistent underestimation of the same magnitude at both time points (Pearson correlation = 0.806). IVUS yielded low accuracy (95% CI of the difference: 0.77; 3.74 and −1.15; 3.27 mm
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for baseline and 6 months, respectively), with several outliers and random variability test–retest. Minimal lumen area (MLA) decreased substantially between baseline and 6 months on QCA and OCT and only minimally on IVUS (95% CI: 0.11; 0.42). Agreement between the different imaging modalities is poor: worst agreement Videodensitometry-IVUS post-implantation (ICCa 0.289); best agreement IVUS-OCT at baseline (ICCa 0.767). All pairs deviated significantly from linearity (
P
< 0.01). Passing-Bablok non-parametric orthogonal regression showed constant and proportional bias between IVUS and OCT. OCT is the most accurate technique for measuring stent length, whilst QCA incurs systematic underestimation (foreshortening) and solid state IVUS incurs random error. Volumetric calculations using solid state IVUS are therefore not reliable. There is poor agreement for MLA estimation between all the imaging modalities studied, including IVUS-OCT, hence their values are not interchangeable.
Objectives The aim of this study was to compare the findings of near-infrared spectroscopy (NIRS), intravascular ultrasound (IVUS) virtual histology (VH), and grayscale IVUS obtained in matched ...coronary vessel segments of patients undergoing coronary angiography. Background Intravascular ultrasound VH has been developed to add tissue characterization to the grayscale IVUS assessment of coronary plaques. Near-infrared spectroscopy is a new imaging technique able to identify lipid core-containing coronary plaques (LCP). Methods We performed NIRS and IVUS-VH pullbacks in a consecutive series of 31 patients with a common region of interest (ROI) between 2 side branches. For each ROI, we analyzed the chemogram blocks by NIRS, plaque area and plaque burden by grayscale IVUS, and tissue types by IVUS-VH. The chemogram block is a summary metric of a 2-mm vertical slice of the chemogram. The value ranges from 0 to 1 according to the presence of lipids and represents the probability of LCP with a color scale from red (low probability) through orange and tan to yellow (high probability). Results Plaque area (mm2 ) increases as percentage VH derived-necrotic core (NC) content (4.6 ± 2.7 vs. 7.4 ± 3.5 vs. 8.6 ± 3.4 vs. 7.9 ± 3.3, grouped in percentage NC quartiles, p < 0.001) and chemogram block probability color bin thresholds increase (4.9 ± 3.8 red, 7.3 ± 3.6 orange, 8.1 ± 3.4 tan, and 8.7 ± 3.4 yellow, p < 0.001). The correlation between the block chemogram detection of lipid core and percentage NC content by VH was weak (r = 0.149). Correction for the presence of calcium does not improve this correlation. Conclusions Larger plaque area by grayscale IVUS was more often associated with either elevated percentage VH-NC or LCP by NIRS; however, the correlation between the detection of LCP by NIRS and necrotic core by VH is weak.
The aim of this study was to identify independent correlates of very late scaffold thrombosis (VLST) from an analysis of consecutively treated patients from 15 multicenter studies.
Recent analyses ...suggest an increased risk for VLST with the Absorb Bioresorbable Vascular Scaffold compared with drug-eluting stents, but insights as to correlates of risk are limited.
A total of 55 patients were identified with scaffold thrombosis. They were matched 2:1 with control subjects selected randomly from patients without thrombosis from the same study. Quantitative coronary angiography was available for 96.4% of patients. Multiple logistic and Cox regression analysis were used to identify significant independent outcome correlates from 6 pre-specified characteristics.
Patients had scaffold thrombosis at a median of 20 months (interquartile range: 17 to 27 months). Control subjects were followed for 36 months (interquartile range: 24 to 38 months). For the combined groups, reference vessel diameter (RVD) was 2.84 ± 0.50 mm, scaffold length was 26 ± 16 mm, and post-dilatation was performed in 56%. Univariate correlates of thrombosis were smaller nominal scaffold/RVD ratio (linear p = 0.001; ratio <1.18:1; odds ratio: 7.5; p = 0.002) and larger RVD (linear p = 0.001; >2.72 mm; odds ratio: 3.4; p = 0.001). Post-dilatation at ≥16 atm, post-dilatation balloon/scaffold ratio, final percentage stenosis, and dual antiplatelet therapy were not correlated with VLST. Only scaffold/RVD ratio remained a significant independent correlate of VLST (p = 0.001), as smaller ratio was correlated with RVD (p < 0.001). Post hoc analysis of 8 other potential covariates revealed no other correlates of outcome.
In the present analysis, the largest to date of its type, relative scaffold undersizing was the strongest determinant of VLST. Given current understanding of “scaffold dismantling,” this finding likely has ramifications for all bioresorbable scaffolds.
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Objectives We investigated the 6-month clinical outcomes after implantation of second-generation 3.0-mm bioresorbable everolimus-eluting vascular scaffolds (BVS) in small coronary vessels (<2.5 mm). ...Background BVS are a novel approach to treating coronary lesions and are untested in small vessels. Methods The ABSORB Cohort B Trial is a multicenter, single-arm, prospective, open-label trial assessing the performance of the second-generation BVS, in which 101 patients were enrolled. The pre-procedural reference vessel diameter (RVD) was assessed by quantitative coronary angiography during post hoc analysis. The vessel size was overestimated, by visual assessment, in 41 patients before implantation of 3.0-mm BVS in vessels with a pre-procedural RVD <2.5 mm. The study population was divided into 2 groups, group I (n = 41) with RVD <2.5 mm and group II (n = 60) with RVD ≥2.5 mm. The composite endpoint of ischemia-driven major adverse cardiac events, defined as ischemia-driven target lesion revascularization, myocardial infarction, or cardiac death, was assessed. Of the 45 patients scheduled for 6-month coronary angiography, 42 patients had the procedure performed, with intravascular ultrasound undertaken in 40 of these patients. Results At 6 months, no significant differences in ischemia-driven major adverse cardiac events (3 of 41 7.3% cases vs. 2 of 60 3.3% cases; p = 0.3933) were observed in the small- and large-vessel groups, respectively. No cardiac deaths or episodes of in-scaffold thromboses were seen. Angiographic and intravascular ultrasound follow-up demonstrated no differences in late lumen loss (0.16 ± 0.18 mm vs. 0.21 ± 0.17 mm; p = 0.3525) or percentage lumen area stenosis (17.6 ± 6.0% vs. 19.8 ± 8.5%; p = 0.3643). Conclusions The second-generation 3.0-mm BVS appears to be safe in small vessels, with similar clinical and angiographic outcomes compared with those of large vessels.
Objectives This study sought to assess the vascular function in patients with chronic total coronary occlusions (CTO) immediately after successful percutaneous recanalization and its relation with ...the pre-existing collateral circulation. Background CTOs represent a long-acting occlusion of a coronary vessel, in which the progressively developed collateral circulation may limit ischemia and symptoms. However, it is unknown if the coronary segment distal to the occlusion has a preserved vascular function. Methods We prospectively enrolled 19 consecutive patients, after percutaneous coronary intervention of a CTO. Luminal diameter, measured by quantitative coronary angiography, and coronary blood flow at level of epicardial coronary artery distal to the treated CTO was assessed before and after administration of acetylcholine (Ach), adenosine, and nitroglycerin (NTG). Collaterals were assessed angiographically by grading of Rentrop and of collateral connections (CC1: threadlike continuous connection; CC2: side branch–like connection). Results Overall, Ach and adenosine caused coronary artery vasoconstriction (p = 0.001 and p = 0.004, respectively), whereas NTG failed to induce vasodilation (p = 0.084). Coronary blood flow significantly decreased with Ach (p = 0.005), significantly increased with NTG (p = 0.035), and did not change with adenosine (p = 0.470). Patients with CC2 collaterals (n = 8) had less vasoconstriction response and reduction in coronary blood flow after Ach (p = 0.005 and p = 0.008, respectively), and better vasomotor response to NTG (p = 0.029) than patients with CC1 collaterals (n = 11). Conclusions Significant endothelial and smooth muscle dysfunction is present in the distal segments of successfully recanalized CTOs, and that seems to be more pronounced in the presence of a low grading of collateral circulation.
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