Yaping Zeng

Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology

Cumulative evidence from histology-based studies demonstrate that the currently available intravascular imaging techniques have fundamental limitations that do not allow complete and detailed evaluation of plaque morphology and pathobiology, limiting the ability to accurately identify high-risk plaques. To overcome these drawbacks, new efforts are developing for data fusion methodologies and the design of hybrid, dual-probe catheters to enable accurate assessment of plaque characteristics, and reliable identification of high-risk lesions. Today several dual-probe catheters have been introduced including combined near infrared spectroscopy-intravascular ultrasound (NIRS-IVUS), that is already commercially available, IVUS-optical coherence tomography (OCT), the OCT-NIRS, the OCT-near infrared fluorescence (NIRF) molecular imaging, IVUS-NIRF, IVUS intravascular photoacoustic imaging and combined fluorescence lifetime-IVUS imaging. These multimodal approaches appear able to overcome limitations of standalone imaging and provide comprehensive visualization of plaque composition and plaque biology. The aim of this review article is to summarize the advances in hybrid intravascular imaging, discuss the technical challenges that should be addressed in order to have a use in the clinical arena, and present the evidence from their first applications aiming to highlight their potential value in the study of atherosclerosis.

Single or dual antiplatelet therapy after PCI

The optimal duration and type of antiplatelet therapy after implantation of a drug-eluting stent (DES) remains uncertain. At the time of the first-in-man implantation of the sirolimus DES in 1999, the protocol-defined dual antiplatelet therapy (DAPT) duration was only 2 months. Subsequently, DAPT duration was extended to 1 year on the basis of anecdotal historical data, and this practice was then incorporated into clinical guidelines. For >1 decade, trialists have sought to compare the safety and efficacy of abbreviated (<6 months) and prolonged (>12 months) DAPT regimens. However, the body of evidence is limited by the heterogeneity of end points, time of randomization, and bleeding criteria used in each trial. Pharmaceutical advances led to the introduction of new ADP-receptor antagonists, which are thought to be more effective than clopidogrel. The ADP-receptor antagonists moved the focus from the optimal duration of DAPT to the potential efficacy of single antiplatelet therapy after DES implantation. In this Review, we summarize the current evidence on the duration of DAPT and the risk of bleeding and adverse cardiac events after DES implantation, and describe the pitfalls of trial interpretation. The ongoing, prospective trials to test single antiplatelet therapy after DES implantation are also discussed.

Is quantitative coronary angiography reliable in assessing the lumen gain after treatment with the everolimus-eluting bioresorbable polylactide scaffold?

AIMS The current study aimed to assess the difference in lumen dimension measurements between optical coherence tomography (OCT) and quantitative coronary angiography (QCA) in the polymeric bioresorbable scaffold and metallic stent. METHODS AND RESULTS In the randomised ABSORB Japan trial, 87 lesions in the Absorb arm and 44 lesions in the XIENCE arm were analysed. Post-procedural OCT-QCA lumen dimensions were assessed in matched proximal/distal non-stented/non-scaffolded reference (n=199), scaffolded (n=145) and stented (n=75) cross-sections at the two device edges using the Bland-Altman method. In the non-stented/non-scaffolded reference segments, QCA systematically underestimated lumen diameter (LD) compared with OCT (accuracy, -0.26 mm; precision, 0.47 mm; 95% limits of agreement as a mean bias±1.96 standard deviation, -1.18-0.66 mm). When compared to OCT, QCA of the Absorb led to a more severe underestimation of the LD (-0.30 mm; 0.39 mm; -1.06-0.46 mm) than with the XIENCE (-0.14 mm; 0.31 mm; -0.75-0.46 mm). QCA underestimated LD by 9.1%, 4.9%, and 9.8% in the reference, stented, and scaffolded segments, respectively. The protrusion distance of struts was larger in the Absorb arm than in the XIENCE arm (135±27 µm vs. 18±26 µm, p<0.001), and may have contributed to the observed differences. CONCLUSIONS In-device QCA measurement was differently affected by the presence of a metallic or polymeric scaffold, a fact that had a significant impact on the QCA assessment of acute gain and post-procedural minimum LD.

Edge Vascular Response After Resorption of the Everolimus-Eluting Bioresorbable Vascular Scaffold - A 5-Year Serial Optical Coherence Tomography Study.

BACKGROUND The edge vascular response (EVR) has been linked to important prognostic implications in patients treated with permanent metallic stents. We aimed to investigate the relationship of EVR with the geometric changes in the everolimus-eluting bioresorbable scaffold using serial optical coherence tomography (OCT) analysis. METHODSANDRESULTS In the first-in-man ABSORB trial, 28 patients (29 lesions) underwent serial OCT at 4 different time points (Cohort B1: post-procedure, 6, 24, and 60 months [n=13]; Cohort B2: post-procedure, 12, 36, and 60 months [n=15]) following implantation of the scaffold. In Cohort B1, there was no significant luminal change at the distal or proximal edge segment throughout the entire follow-up. In contrast, there was a significant reduction of the lumen flow area (LFA) of the scaffold between post-procedure and 6 months (-1.03±0.49 mm(2)[P<0.001]), whereas between 6 and 60 months the LFA remained stable (+0.31±1.00 mm(2)[P=0.293]). In Cohort B2, there was a significant luminal reduction of the proximal edge between post-procedure and 12 months (-0.57±0.74 mm(2)[P=0.017]), whereas the lumen area remained stable (-0.26±1.22 mm(2)[P=0.462]) between 12 and 60 months. The scaffold LFA showed a change similar to that observed in Cohort B1. CONCLUSIONS Our study demonstrated a reduction in the scaffold luminal area in the absence of major EVR, suggesting that the physiological continuity of the lumen contour is restored long term. (Circ J 2016; 80: 1131-1141).

Change in lumen eccentricity and asymmetry after treatment with Absorb bioresorbable vascular scaffolds in the ABSORB Cohort B trial: a five-year serial optical coherence tomography imaging study.

AIMS The aim of the study was to investigate long-term changes in lumen eccentricity and asymmetry at five years after implantation of the Absorb bioresorbable vascular scaffold (BVS). METHODS AND RESULTS Out of 101 patients from the ABSORB cohort B trial, 28 patients (29 lesions) with serial optical coherence tomography (OCT) examination at four different time points (cohort B1: post-procedure, six months, two, and five years [n=13]; cohort B2: post-procedure, one, three, and five years [n=16]) were evaluated. The longitudinal variance in lumen diameter was assessed by asymmetry index (AI). An asymmetric lesion was defined as AI >0.3. The circularity of the lumen or scaffold was evaluated by the eccentricity index calculated as minimal divided by maximal luminal or scaffold diameter per cross-section. The lowest lumen eccentricity index within a scaffold segment (EIL) <0.7 was defined as an eccentric lesion. Post procedure, an eccentric lesion was observed in 72.4% and became concentric in 93.1% at five years (post EIL 0.67±0.05 vs. five-year EIL 0.80±0.10, p=0.03) with a modest reduction of the lumen area from baseline to five years by 0.75±0.32 mm2. Asymmetric lumen morphology was observed in 93.1% (n=27) post implantation and persisted until five-year follow-up. On serial OCT analyses, there was a substantial increase in the scaffold EI during the first two years (post 0.70±0.06, six months 0.76±0.08, two years 0.85±0.07); then, it remained stable whereas the lumen circularity improved further. There were no significant differences in major adverse cardiac events regarding the lumen morphology over the five-year follow-up. CONCLUSIONS In patients treated with the Absorb BVS, the cross-sectional circularity improved over five years while the variance in longitudinal diameters remained. Regaining of lumen circularity is mainly caused by reshaping of the scaffold during the first two years.

Non-invasive Heart Team assessment of multivessel coronary disease with coronary computed tomography angiography based on SYNTAX score II treatment recommendations: design and rationale of the randomised SYNTAX III Revolution trial

AIMS The aim of this study was to investigate whether a Heart Team decision-making process regarding the choice of revascularisation strategy based on non-invasive coronary multislice computed tomography angiography (MSCT) assessment of coronary artery disease (CAD) is equivalent to the standard-of-care invasive angiography-based assessment in patients with multivessel CAD. METHODS AND RESULTS The SYNTAX III Revolution trial is a prospective, multicentre, all-comers randomised trial that will randomise two Heart Teams to select between surgical and percutaneous treatment according to either an invasive conventional angiography or a non-invasive MSCT angiography assessment in patients with multivessel CAD. The treatment selection by each Heart Team will be guided by the SYNTAX score II calculation. The primary endpoint is the level of agreement according to kappa of the initial decision by the Heart Teams on the modality of the revascularisation based on MSCT and angiography assessments. Secondary endpoints include agreement on the number of vessels requiring treatment and the coronary segments in need of revascularisation. CONCLUSIONS The SYNTAX III Revolution trial will provide valuable information regarding the ability of a purely non-invasive coronary anatomy assessment to select accurately the most appropriate revascularisation strategy for patients with multivessel CAD.

Intracoronary optical coherence tomography: Clinical and research applications and intravascular imaging software overview

By providing valuable information about the coronary artery wall and lumen, intravascular imaging may aid in optimizing interventional procedure results and thereby could improve clinical outcomes following percutaneous coronary intervention (PCI). Intravascular optical coherence tomography (OCT) is a light‐based technology with a tissue penetration of approximately 1 to 3 mm and provides near histological resolution. It has emerged as a technological breakthrough in intravascular imaging with multiple clinical and research applications. OCT provides detailed visualization of the vessel following PCI and provides accurate assessment of post‐procedural stent performance including detection of edge dissection, stent struts apposition, tissue prolapse, and healing parameters. Additionally, it can provide accurate characterization of plaque morphology and provides key information to optimize post‐procedural outcomes. This manuscript aims to review the current clinical and research applications of intracoronary OCT and summarize the analytic OCT imaging software packages currently available.

Hemodynamic analysis of a novel bioresorbable scaffold in porcine coronary artery model

The shear stress distribution assessment can provide useful insights for the hemodynamic performance of the implanted stent/scaffold. Our aim was to investigate the effect of a novel bioresorbable scaffold, Mirage on local hemodynamics in animal models.

DIFFERENCE IN HEMODYNAMIC MICRO-ENVIRONMENT IN VESSELS SCAFFOLDED WITH ABSORB BVS AND MIRAGE BRMS: INSIGHTS FROM A PRE-CLINICAL ENDOTHELIAL SHEAR STRESS STUDY

BACKGROUND: In silico studies have provided robust evidence that stent design affects local hemodynamic forces, which appear as a major determinant of clinical outcomes following stent implantation. However, implications of different stent/scaffold configurations on local hemodynamic forces have not yet been investigated in vivo in a comparative fashion. METHOD AND RESULTS: Eight healthy mini pigs were implanted with six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb BVS) and five Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage BRMS). Optical coherence tomography (OCT) was performed and strut protrusion was assessed post scaffold implantation. Following the reconstruction of coronary anatomy blood flow simulation was performed and endothelial shear stress (ESS) was estimated on top of the struts and at luminal surface between the struts in each scaffold. The thicker struts in Absorb (152±140µm) resulted in an increased protruded distance compared to Mirage (117±123 µm) (p=0.003). This had an effect in the local hemodynamic microenvironment. ESS at top-of-the struts were higher in Absorb (1.69±1.20 Pa) than in Mirage (1.53±0.91 Pa), (p<0.001) but lower at inter-strut zones (0.60±0.51Pa vs 0.63±0.50 Pa; p<0.01) compared to Mirage. Both scaffold types revealed comparable percentages of vessel luminal surface exposed to recirculation. CONCLUSION: Absorb demonstrated higher shear stress on top of the struts compared to Mirage. However, in the inter-struts zones shear stress was higher in Mirage than in Absorb. Further research is required to examine potential value of in vivo computational modeling in optimizing scaffold configuration and clinical outcomes.

Coronary bypass surgery versus stenting in multivessel disease involving the proximal left anterior descending coronary artery

Objective In patients with multivessel disease and proximal left anterior descending artery (LAD) involvement, the best revascularisation strategy is still unclear. We assess outcomes after coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI) with drug-eluting stents in a pooled analysis of individual patient-level data of the SYNTAX and BEST randomised trials. Design Proximal LAD involvement was defined by any lesion ≥ 50% diameter stenosis in the arterial segment starting from the left-main bifurcation up to (and including) the origin of the first major septal branch. The primary endpoint was the composite of all-cause death, myocardial infarction (MI) or stroke at 5 years of follow-up. Results The present study population comprises 1166 patients of which 577 were randomised to PCI and 589 to CABG. Baseline characteristics were well balanced across study arms. The primary endpoint occurred in 94 (16.3%) patients in the PCI arm and in 68 (11.5%) patients in the CABG arm (HR 1.43; 95%CI 1.05 to 1.95; p=0.026). CABG was also associated with a significantly lower rate of cardiac death (p=0.007), MI (p<0.001), all-cause revascularisation (p<0.001) and major adverse cardiovascular and cerebrovascular events (all-cause death, MI, stroke, revascularisation) (p<0.001). The rates of all-cause mortality (p=0.06) and stroke (p=0.09) were not statistically different between the two groups. The overall study results for the primary outcome were consistent across several subgroups. Conclusions In patients with multivessel disease with proximal LAD involvement, CABG is associated with lower rates of the safety composite endpoint of death, MI or stroke as compared with PCI with drug-eluting stents at 5 years of follow-up (number needed to treat=21). Trial registration number PRECOMBAT clinicaltrials.gov NCT00997828; SYNTAX: clinicaltrials.gov identifier: NCT00114972 NCT00114972.