Arterial Remodeling After Bioresorbable Scaffolds and Metallic Stents. J Am Coll Cardiol. 2017;70:60-74. [PMID: 28662808 DOI: 10.1016/j.jacc.2017.05.028]

Long-term efficacy, safety and biocompatibility of a novel sirolimus eluting iron bioresorbable scaffold in a porcine model

Iron is considered as an attractive alternative material for bioresorbable scaffolds (BRS). The sirolimus eluting iron bioresorbable scaffold (IBS), developed by Biotyx Medical (Shenzhen, China), is the only iron-based BRS with an ultrathin-wall design. The study aims to investigate the long-term efficacy, safety, biocompatibility, and lumen changes during the biodegradation process of the IBS in a porcine model. A total of 90 IBSs and 70 cobalt-chromium everolimus eluting stents (EES) were randomly implanted into nonatherosclerotic coronary artery of healthy mini swine. The multimodality assessments including coronary angiography, optical coherence tomography, micro-computed tomography, magnetic resonance imaging, real-time polymerase chain reaction (PCR), and histopathological evaluations, were performed at different time points. There was no statistical difference in area stenosis between IBS group and EES group at 6 months, 1year, 2 years and 5 years. Although the scaffolded vessels narrowed at 9 months, expansive remodeling with increased mean lumen area was found at 3 and 5 years. The IBS struts remained intact at 6 months, and the corrosion was detectable at 9 months. At 5 years, the iron struts were completely degraded and absorbed in situ, without in-scaffold restenosis or thrombosis, lumen collapse, aneurysm formation, and chronic inflammation. No local or systemic toxicity and abnormal histopathologic manifestation were found in all experiments. Results from real-time PCR indicated that no sign of iron overload was reported in scaffolded segments. Therefore, the IBS shows comparable efficacy, safety, and biocompatibility with EES, and late lumen enlargement is considered as a unique feature in the IBS-implanted vessels.

Structural and Functional Evaluation of Coronary Arteries Treated With ABSORB Bioresorbable Vascular Scaffold at 5-Year Follow-Up

Although complete bioresorbable vascular scaffold (BVS) resorption has been demonstrated at 5-year follow-up, whether corresponding vasomotor function restoration occurs remains unknown. The objective was to simultaneously assess the structural healing response along with vasomotor responses at 5-year follow-up of BVS implantation. We studied consecutive patients treated with ABSORB-BVS at 5-year follow-up (n = 31), who were recruited from a multicenter registry and were contacted to undergo a research protocol-driven repeat coronary angiogram involving intracoronary optical coherence tomography (OCT) and invasive coronary endothelial function testing. Epicardial endothelium-dependent vasomotion was defined as any vasodilatation after intracoronary acetylcholine (ACh), whereas endothelium-independent vasomotion was defined as any vasodilatation after intracoronary nitroglycerine (NTG), using quantitative coronary angiography. The mean implantation time point was 60.5 ± 4.6 months. OCT imaging demonstrated complete scaffold resorption in all patients. New coronary lesions (stenosis >50%) were found in 5 patients (16.1%), 3 of them underwent ad hoc percutaneous revascularization (9.7%). Intracoronary ACh (27 patients) and NTG testing (30 patients) was performed. Quantitative coronary angiography analysis demonstrated vasoconstriction after ACh administration and lack of response to NTG in BVS segments (mean lumen diameter = 2.00 ± 0.61 mm at baseline vs 1.74 ± 0.70 mm post-ACh, p <0.001; 2.05 ± 0.54 mm at baseline vs 2.03 ± 0.50 mm post-NTG, p = 0.69). OCT lumen analysis demonstrated similar vasoconstrictive responses to ACh (mean lumen area = 5.31 ± 2.26 mm² at baseline vs 5.12 ± 2.55 mm² post-ACh, p = 0.007) but had a vasodilatory response to NTG (5.96 ± 2.35 mm² at baseline vs 6.17 ± 2.55 mm² post-NTG, p<0.001). In conclusion, complete ABSORB-BVS resorption was demonstrated at 5-year follow-up. However, this healing response was associated with endothelium-dependent vasomotor dysfunction within the BVS segment.

Five-year comparative study of thin-strut rapamycin-eluting bioabsorbable scaffold with metallic drug-eluting stent in porcine coronary artery

Objectives

Using quantitative coronary angiography (QCA), optical coherence tomography (OCT), histomorphometry, and pharmacokinetics, this study tried to evaluate the safety and efficacy of Biomagic rapamycin-eluting bioabsorbable scaffold (BVS) in non-atherosclerotic porcine coronary arteries.

Background

Biomagic BVS is a new generation of thin-strut bioabsorbable scaffold. We conducted comparative study detailing pathological response, safety and efficacy of Biomagic BVS and the Firebird2 rapamycin-eluting cobalt-based alloy stent (DES) in a porcine coronary artery model. The animals were followed up at 14 days, 1, 3, 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 months after stent implantation.

Methods

A total of 143 devices (95 Biomagic and 48 Firebird2) were implanted in 2 or 3 main coronary arteries of 76 nonatherosclerotic swine and examined by QCA, OCT, light microscopy, and pharmacokinetics analyses at various time points.

Results

Vascular responses to Biomagic and Firebird2 were largely comparable at all time points, with struts being sequestered within the neointima. The degree of inflammation of both devices was mild to moderate, although the Biomagic score was higher at 14 days to 24 months. However, there was no statistical difference between the two groups except 14 days. At each follow-up time point, the percentage of area stenosis in the Biomagic group was greater than that in the Firebird 2 group, but there was no statistical difference between the two groups at 3 and 12 months. The extent of fibrin deposition was similar between Biomagic and Firebird2, which peaked at 1 month and decreased rapidly thereafter. Pharmacokinetic study showed that coronary tissue sirolimus concentration remained above 2 ng/mg of tissue at 28 day. Histomorphometry showed expansile remodeling of Biomagic-implanted arteries starting after 12 months, and lumen area was significantly greater in Biomagic than Firebird2 at 36 and 42 months. These changes correlated with dismantling of Biomagic seen after 12 months. OCT images confirmed that degradation of Biomagic was complete by 36 months.

Conclusions

Biomagic demonstrates comparable long-term safety to Firebird2 in porcine coronary arteries with mild to moderate inflammation. Although Biomagic was associated with greater percent stenosis relative to Firebird2 within 36 months, expansile remodeling was observed after 12 months in Biomagic with significantly greater lumen area at ≥36 months. Scaffold resorption is considered complete at 36 months.

Comparative Appraisal of Intravascular Ultrasound and Optical Coherence Tomography in Invasive Coronary Imaging: 2022 Update

Although coronary angiography has been well established as a standard modality for percutaneous coronary intervention guidance, recent developments in intravascular imaging techniques, such as intravascular ultrasound and optical coherence tomography, have become increasingly adopted, enabling direct detailed lesion visualization, including lesions beyond the scope of assessment using exclusively angiography. Intravascular imaging modalities have been reported to potentially improve both short- and long-term percutaneous intervention outcomes. This review aims to provide a comparative summary of recent advancements in research regarding the clinical applications and outcomes of intravascular ultrasound and optical coherence tomography.

Long-Term Intracoronary Structural and Vasomotor Assessment of the ABSORB Bioresorbable Vascular Scaffold

We systematically categorized the longer-term (≥3 years) structural and functional characteristics of the ABSORB bioresorbable vascular scaffold (BVS) using optical coherence tomography imaging and coronary vasomotor reactivity testing and further compared the functional characteristics of BVS stented versus remote coronary segments. A total of 92 patients (mean age 56.4 ± 9.7 years, 22.8% women) who underwent percutaneous coronary intervention (76% with acute coronary syndrome) using the ABSORB BVS (112 lesions) were included. Optical coherence tomography analysis (38,790 visible struts) comprised in-segment quantitative lumen/plaque and semiquantitative plaque composition analysis of the neointimal pattern. Epicardial endothelium-dependent and-independent vasomotion was defined as any vasodilatation at low/intermediate intracoronary dose of acetylcholine (ACh) and nitroglycerine, assessed using quantitative coronary angiography. At a median time of 3.2 years follow-up, 79.8% of BVS segments still demonstrated visible struts with a predominant neointimal fibrotic healing pattern in 84% of BVS segments, with 99.5% of struts demonstrating coverage with apposition. Compared with remote segments, BVS segments demonstrated less endothelium-dependent vasodilatation at low (p = 0.06) and intermediate ACh doses (p = 0.04). Hypertension, longer time interval from index percutaneous coronary intervention, and the degree of in-BVS segment neointimal volume (p <0.03 for all) were each independently associated with abnormal BVS endothelium-dependent vasomotor function. Endothelium-independent function was more likely preserved in non-BVS (remote) segments compared with BVS segments (p = 0.06). In conclusion, at 3+ years post-ABSORB BVS insertion, the rate of complete scaffold resorption was low and residual strut presence was high, with a dominant fibrous healing response contributing toward neointimal hyperplasia and endothelium-dependent and-independent vasomotor dysfunction.

Applying Principles of Regenerative Medicine to Vascular Stent Development

Stents are a widely-used device to treat a variety of cardiovascular diseases. The purpose of this review is to explore the application of regenerative medicine principles into current and future stent designs. This review will cover regeneration-relevant approaches emerging in the current research landscape of stent technology. Regenerative stent technologies include surface engineering of stents with cell secretomes, cell-capture coatings, mimics of endothelial products, surface topography, endothelial growth factors or cell-adhesive peptides, as well as design of bioresorable materials for temporary stent support. These technologies are comparatively analyzed in terms of their regenerative effects, therapeutic effects and challenges faced; their benefits and risks are weighed up for suggestions about future stent developments. This review highlights two unique regenerative features of stent technologies: selective regeneration, which is to selectively grow endothelial cells on a stent but inhibit the proliferation and migration of smooth muscle cells, and stent-assisted regeneration of ischemic tissue injury.

CCR5 antagonist treatment inhibits vascular injury by regulating NADPH oxidase 1

BACKGROUND

Chemokine (C- Cmotif) ligand 5 (CCL5) and its receptor C-C motif chemokine receptor 5 (CCR5), have been broadly studied in conjunction with infectious pathogens, however, their involvement in cardiovascular disease is not completely understood. NADPH oxidases (Noxs) are the major source of reactive oxygen species (ROS) in the vasculature. Whether the activation of Noxs is CCL5/CCR5 sensitive and whether such interaction initiates vascular injury is unknown. We investigated whether CCL5/CCR5 leads to vascular damage by activating Noxs.

MATERIAL AND METHODS

We used rat aortic smooth muscle cells (RASMC) to investigate the molecular mechanisms by which CCL5 leads to vascular damage and carotid ligation (CL) to analyze the effects of blocking CCR5 on vascular injury.

RESULTS

CCL5 induced Nox1 expression in concentration and time-dependent manners, with no changes in Nox2 or Nox4. Maraviroc pre-treatment (CCR5 antagonist, 40uM) blunted CCL5-induced Nox1 expression. Furthermore, CCL5 incubation led to ROS production and activation of Erk1/2 and NFkB, followed by increased vascular cell migration, proliferation, and inflammatory markers. Notably, Nox1 inhibition (GKT771, 10uM) blocked CCL5-dependent effects. In vivo, CL induced pathological vascular remodeling and inflammatory genes and increased Nox1 and CCR5 expression. Maraviroc treatment (25 mg/Kg/day) reduced pathological vascular growth and Nox1 expression.

CONCLUSIONS

Our findings suggest that CCL5 activates Nox1 in the vasculature, leading to vascular injury likely via NFkB and Erk1/2. Herein, we place CCR5 antagonists and/or Nox1 inhibitors might be preeminent antiproliferative compounds to reduce the cardiovascular risk associated with medical procedures (e.g. angioplasty) and vascular diseases associated with vascular hyperproliferation.

Vasculature-on-chip for Assessment of Bioresorbable Scaffolds and Endothelial Barrier Integrity

ABSTRACT

Endothelial cells adhere to one another through junctional structures formed by intercellular adhesion molecules. These intercellular proteins regulate barrier function in response to the hemodynamic shear rate and enable the selective passage of solutes and fluids across the endothelium. After endovascular device implantation, the endothelial barrier is compromised and becomes discontinuous, which increases permeability, allowing transmigration of leukocytes and lipoproteins and leading to the accumulation of lipid-laden foamy macrophages in the subendothelial space. Drug-coated bioresorbable vascular scaffold implants have been associated with unexpected thrombotic complications, which were not predicted in animals because of dissimilarities in endothelial regeneration and realignment between animals and humans. The development of a microengineered, microfluidics-based system of patterned channels lined with human endothelial and smooth muscle cells perfused with blood allows for the evaluation of endothelial function and barrier integrity. This review highlights the translational potential of vasculature-on-chip, which recreates the microphysiological milieu to evaluate the impact of drug-eluting bioresorbable vascular scaffolds on endothelial barrier integrity and to characterize polymer biodegradation behavior and drug release kinetic profiles over time.

Five-year angiographic, OCT and clinical outcomes of a randomized comparison of everolimus and biolimus-eluting coronary stents with everolimus-eluting bioresorbable vascular scaffolds

Aims

To compare 5‐year angiographic, optical coherence tomography (OCT), and clinical outcomes between patients treated with bioresorbable vascular scaffolds (BVS) and drug‐eluting stents (DES).

Methods

The EverBio‐2 trial (Comparison of Everolimus‐ and Biolimus‐Eluting Coronary Stents with Everolimus‐Eluting Bioresorbable Vascular Scaffold) was a single‐center, assessor‐blinded, randomized controlled trial in which 240 patients were randomly allocated (1:1:1) to BVS, everolimus‐eluting (EES) or biolimus‐eluting (BES) DES. Clinical follow‐up was scheduled up to 5 years. All patients, alive and who did not have repeat revascularization of the target lesion during follow‐up were asked to return for angiographic follow‐up at 5 years.

Results

Five‐year angiographic follow‐up was completed in 122 patients (51%) and OCT analysis was performed in 86 (36%) patients. In‐stent late lumen loss was similar in both groups with 0.50 ± 0.38 mm in BVS versus 0.58 ± 0.36 mm in EES/BES, p = 0.20. Clinical follow‐up was complete in 232 patients (97%) at 5 years. The rate of the device‐oriented endpoint was 22% in the BVS and 18% in the EES/BES group (p = 0.49). The patient‐oriented composite endpoint occurred in 40% of BVS‐ and 43% of EES/BES‐treated patients (p = 0.72) at 5 years. No acute coronary syndrome due to stent thrombosis was detected after 2 years. Complete BVS strut resorption was observed at 5 years in the OCT subgroup.

Conclusion

Five‐year clinical outcomes were similar between BVS and DES patients as well as angiographic outcomes in a selected subgroup. However, a definitive conclusion cannot be drawn because the EverBio‐2 trial was not powered for clinical and angiographic endpoints at 5 years of follow‐up.

Modelling Stretch Blow Moulding of Poly (l-lactic acid) for the Manufacture of Bioresorbable Vascular Scaffold

Stretch blow moulding (SBM) has been employed to manufacture bioresorbable vascular scaffold (BVS) from poly (l-lactic acid) (PLLA), whilst an experience-based method is used to develop the suitable processing conditions by trial-and-error. FEA modelling can be used to predict the forming process by the scientific understanding on the mechanical behaviour of PLLA materials above the glass transition temperature (T_g). The applicability of a constitutive model, the ‘glass-rubber’ (GR) model with material parameters from biaxial stretch was examined on PLLA sheets replicating the biaxial strain history of PLLA tubes during stretch blow moulding. The different stress–strain relationship of tubes and sheets under equivalent deformation suggested the need of re-calibration of the GR model for tubes. A FEA model was developed for PLLA tubes under different operation conditions, incorporating a virtual cap and rod to capture the suppression of axial stretch. The reliability of the FEA modelling on tube blowing was validated by comparing the shape evolution, strain history and stress–strain relationship from modelling to the results from the free stretch blow test.

Positive Remodeling – a Major Feature of Vulnerability in Patients with Non-Obstructive Coronary Artery Disease

The most common cause of acute coronary syndrome is thrombosis of an atheromatous plaque. Positive remodeling is the compensatory dilatation of the plaque-containing section of the vessel wall. Plaques are most commonly characterized as vulnerable when possessing some of the following features: fibrous cap thickness <65 µm, large necrotic lipid core, high degrees of inflammatory infiltrates, positive remodeling, intraplaque hemorrhage, or neoangio-genesis. The presence of these plaque features is associated with high cardiovascular risk. In the initial stage of vasculopathy, due to positive remodeling, lumen reduction is not typical; it only develops in the advanced phase of the disease, due to which, based on a lumenogram, the vascular system may appear intact. Therefore, coronary angiography can easily miss the diagnosis or underestimate its extent, since it does not inform us of the composition of the arterial wall, because the contrast agent is just filling the vessel lumen. Coronary CT angiography may fill this diagnostic gap, since changes of the vessel wall can directly be visualized. To increase diagnostic accuracy, invasive coronary angiography can be completed by intravascular ultrasound and optical coherence tomography.

Long-Term Arterial Remodeling After Bioresorbable Scaffold Implantation 4-Year Follow-up of Quantitative Coronary Angiography, Histology and Optical Coherence Tomography

PURPOSE

Our previous studies have confirmed the safety and efficacy of the novel fully bioresorbable PLLA scaffold (PowerScaffold®) at 12 months implantation. In the present study, the scaffold absorption and coronary vessel remodeling at 4 years were evaluated.

METHODS

After PowerScaffold® were implanted into 13 coronary arteries of 6 miniature pigs, quantitative coronary angiography (QCA) was performed at 15 days and 4 years follow-up to measure the mean lumen diameter (MLD), late lumen loss (LLL), and % stenosis of the coronary arteries. Optical coherence tomography (OCT) was performed to obtain the strut footprints at 4 years before euthanization for histological analysis. In addition, 2 PowerScaffold® were implanted into 2 miniature pigs for 2 years as supplementary data. All stented arteries were dissected and stained with HE, Masson, EVG, and Alcian blue to observe struts, cells, fibrinoid, elastin, and proteoglycans, respectively.

RESULTS

There were no significant differences in MLD, LLL and % stenosis in stented coronary arteries between 15 days and 4 years by QCA. At 4 years, most strut sites were indiscernible and replaced by extracellular matrix and connective tissue by histology. Both strut/vessel wall interaction and strut coverage were shown 100% by OCT.

CONCLUSION

At 4 years, the scaffold struts were completely embedded into vessel wall and mostly replaced by regenerated tissue. There was no sign of in-stent stenosis in all stented arteries.

Randomized Comparison Between Everolimus-Eluting Bioresorbable Scaffold and Metallic Stent: Multimodality Imaging Through 3 Years

OBJECTIVES

The aim of this study was to investigate the vascular responses and fates of the scaffold after bioresorbable vascular scaffold (BVS) implantation using multimodality imaging.

BACKGROUND

Serial comprehensive image assessments after BVS implantation in the context of a randomized trial have not yet been reported.

METHODS

In the ABSORB Japan trial, 400 patients were randomized to a BVS (n = 266) or a cobalt-chromium everolimus-eluting stent (n = 134). Through 3 years, patients underwent serial angiography and intravascular ultrasound or optical coherence tomography (OCT).

RESULTS

Luminal dimension at 3 years was consistently smaller with the BVS than with the cobalt-chromium everolimus-eluting stent (mean angiographic minimal luminal diameter 2.04 ± 0.63 mm vs. 2.40 ± 0.56 mm, mean difference -0.37 mm [95% confidence interval: -0.50 to -0.24 mm]; p < 0.001), mainly because of smaller device area (6.13 ± 2.03 mm² vs. 7.15 ± 2.16 mm², mean difference -1.04 mm² [95% confidence interval: -1.66 to -0.42 mm²]; p < 0.001), and larger neointimal area (2.10 ± 0.61 mm² vs. 1.86 ± 0.64 mm², mean difference 0.24 mm² [95% confidence interval: 0.06 to 0.43 mm²]; p = 0.01) by OCT. BVS-treated vessels did not show previously reported favorable vessel responses, such as positive vessel remodeling, late luminal enlargement, and restoration of vasomotion, although the OCT-based healing score was on average zero (interquartile range: 0.00 to 0.00). At 3 years, intraluminal scaffold dismantling (ISD) was observed in 14% of BVS. On serial OCT, ISD was observed in 6 lesions at 2 years, where the struts had been fully apposed at post-procedure, while ISD was observed in 12 lesions at 3 years, where 8 lesions were free from ISD on 2-year OCT. In 5 cases of very late scaffold thrombosis, strut discontinuities were detected in all 4 cases with available OCT immediately before reintervention.

CONCLUSIONS

In this multimodality serial imaging study, luminal dimension at 3 years was smaller with the BVS than with the cobalt-chromium everolimus-eluting stent. ISD, suspected to be one of the mechanisms of very late BVS thrombosis, was observed in a substantial proportion of cases at 3 years, which developed between post-procedure and 2 years and even beyond 2 years. (AVJ-301 Clinical Trial: A Clinical Evaluation of AVJ-301 [Absorb™ BVS] in Japanese Population [ABSORB JAPAN]; NCT01844284).

Endothelial shear stress and vascular remodeling in bioresorbable scaffold and metallic stent

BACKGROUND AND AIMS

The impact of endothelial shear stress (ESS) on vessel remodeling in vessels implanted with bioresorbable scaffold (BRS) as compared to metallic drug-eluting stent (DES) remains elusive. The aim of this study was to determine whether the relationship between ESS and remodeling patterns differs in BRS from those seen in metallic DES at 3-year follow-up.

METHODS

In the ABSORB II randomized trial, lesions were investigated by serial coronary angiography and intravascular ultrasound (IVUS). Three-dimensional reconstructions of coronary arteries post-procedure and at 3 years were performed. ESS was quantified using non-Newtonian steady flow simulation. IVUS cross-sections in device segment were matched using identical landmarks.

RESULTS

Paired ESS calculations post-procedure and at 3 years were feasible in 57 lesions in 56 patients. Post-procedure, median ESS at frame level was higher in BRS than in DES, with marginal statistical significance (0.97 ± 0.48 vs. 0.75 ± 0.39 Pa, p = 0.063). In the BRS arm, vessel area and lumen area showed larger increases in the highest tercile of median ESS post-procedure as compared to the lowest tercile. In contrast, in DES, no significant relationship between median ESS post-procedure and remodeling was observed. In multivariate analysis, smaller vessel area, larger lumen area, higher plaque burden post-procedure, and higher median ESS post-procedure were independently associated with expansive remodeling in matched frames. Only in BRS, younger age was an additional significant predictor of expansive remodeling.

CONCLUSIONS

In a subset of lesions with large plaque burden, shear stress could be associated with expansive remodeling and late lumen enlargement in BRS, while ESS had no impact on vessel dimension in metallic DES.

The 2010s in clinical drug-eluting stent and bioresorbable scaffold research: a Dutch perspective

Dutch researchers were among the first to perform clinical studies in bare metal coronary stents, the use of which was initially limited by a high incidence of in-stent restenosis. This problem was greatly solved by the introduction of drug-eluting stents (DES). Nevertheless, enthusiasm about first-generation DES was subdued by discussions about a higher risk of very-late stent thrombosis and mortality, which stimulated the development, refinement, and rapid adoption of new DES with more biocompatible durable polymer coatings, biodegradable polymer coatings, or no coating at all. In terms of clinical DES research, the 2010s were characterised by numerous large-scale randomised trials in all-comers and patients with minimal exclusion criteria. Bioresorbable scaffolds (BRS) were developed and investigated. The Igaki-Tamai scaffold without drug elution was clinically tested in the Netherlands in 1999, followed by an everolimus-eluting BRS (Absorb) which showed favourable imaging and clinical results. Afterwards, multiple clinical trials comparing Absorb and its metallic counterpart were performed, revealing an increased rate of scaffold thrombosis during follow-up. Based on these studies, the commercialisation of the device was subsequently halted. Novel technologies are being developed to overcome shortcomings of first-generation BRS. In this narrative review, we look back on numerous devices and on the DES and BRS trials reported by Dutch researchers.

Peri-strut low intensity areas and in-scaffold neointima growth after bioresorbable scaffold implantation in STEMI. A serial optical coherence tomography study

BACKGROUND

Peri-strut low intensity areas (PLIA) visualized by optical coherence tomography (OCT) have been related to neointimal proliferation and increased incidence of target lesion revascularization in stable coronary artery disease. The aim of this study was to determine the association between PLIA by OCT and the long-term vascular healing response after bioresorbable scaffold (BRS) implantation in the setting of ST-segment elevation myocardial infarction (STEMI).

METHODS

This is a single-centre, longitudinal, cohort study with a serial: baseline, 1, 2 and 5 years OCT evaluation of neointimal response (lumen area and neoatherosclerosis) after percutaneous coronary intervention (PCI) with BRS Absorb™ 1.0 implantation in patients presenting with STEMI. PLIA was analyzed in every cross section and scored: 0-no PLIA; 1-PLIA < 1 quadrant; 2-PLIA ≥ 1 and <2 quadrants; 3-PLIA ≥ 2 and <3 quadrants; 4-PLIA in ≥3 quadrants.

RESULTS

Of the 23 patients implanted BRS, 18 completed 2-year follow-up, whereas complete OCT data up to 5 years were available in 12 patients. Presence of PLIA was identified in 100% patients at 1 and 2 years, whereas at 5 years neither PLIA nor scaffold struts were visualized by OCT. Neoatherosclerosis was identified in 73,68% patients after 1 year and in all patients at 2 and 5 years. The mean PLIA score > 1 at 2 years was associated with greater percentage of minimum lumen area decrease after 2 years from index procedure.

CONCLUSIONS

The extent of PLIA by OCT at 2 years after primary PCI with BRS was associated with lumen area decrease. Neoatherosclerosis formation was detected in all patients at 2 and 5 years. PLIA assessment could serve as an additive means to predict neointimal healing pattern after next generation BRS implantation.

Advances in IVUS/OCT and Future Clinical Perspective of Novel Hybrid Catheter System in Coronary Imaging

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been developed and improved as both diagnostic and guidance tools for interventional procedures over the past three decades. IVUS has a resolution of 100 μm with a high tissue penetration and capability of assessing the entire structure of a coronary artery including the external elastic membrane, whereas OCT has a higher resolution of 10–20 μm to assess endoluminal structures with a limited tissue penetration compared to IVUS. Recently, two companies, CONAVI and TERUMO, integrated IVUS and OCT into a single catheter system. With their inherent strength and limitations, the combined IVUS and OCT probes are complementary and work synergistically to enable a comprehensive depiction of coronary artery. In this review, we summarize the performance of the two intracoronary imaging modalities—IVUS and OCT—and discuss the expected potential of the novel hybrid IVUS–OCT catheter system in the clinical field.

Impact of Coronary Atherosclerosis on Bioresorbable Vascular Scaffold Resorption and Vessel Wall Integration

•

The bioresorption process of the Absorb BVS has been directly characterized only in a normal swine model and indirectly (by imaging surrogates) in clinical studies.

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Using multimodality imaging and histology, this study indicates that in a diseased animal model, the resorption and integration of BVS into the arterial wall is not affected by the presence of untreated hyperlipidemia and atherosclerosis progression.

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Imaging and histology suggest that BVS degradation progresses similarly in the presence of atherosclerosis compared with earlier data from nonatherosclerotic arteries. However, BVS is not immune to the development of neoatherosclerosis.

The integration of the Absorb bioresorbable vascular scaffold (BVS) into the arterial wall has never been tested in an in vivo model of atherosclerosis. This study aimed to compare the long-term (up to 4 years) vascular healing responses of BVS to an everolimus-eluting metallic stent in the familial hypercholesterolemic swine model of atherosclerosis. The multimodality imaging and histology approaches indicate that the resorption and vascular integration profile of BVS is not affected by the presence of atherosclerosis. BVS demonstrated comparable long-term vascular healing and anti-restenotic efficacy to everolimus-eluting metallic stent but resulted in lower late lumen loss at 4 years.

A paradox in sex-specific clinical outcomes after bioresorbable scaffold implantation: 2-year results from the AIDA trial

BACKGROUND

Females are underrepresented in clinical trials evaluating new stent technologies whilst results may differ between the sexes. Females are known to have smaller, more tortuous coronary arteries and have generally more comorbidities. On the other hand, they may have smaller plaque burden. This subgroup-analysis sought to assess sex-specific outcomes after Absorb bioresorbable vascular scaffold (BVS) or XIENCE everolimus-eluting stent (EES) implantation.

METHODS

The AIDA trial was an investigator-initiated, non-inferiority, all-comers trial, in which 1845 patients were randomly assigned to either Absorb BVS or XIENCE EES. Baseline clinical, angiography and procedural variables, as well as 2-year clinical outcomes were analyzed by sex and device modality.

RESULTS

Of the 1845 randomized patients, 475 (25.7%) were females. The 2-year rates of target vessel failure (TVF) with Absorb BVS versus XIENCE EES in females were 6.4% versus 10.6% (HR 0.59; 95% CI: 0.31-1.11; p = 0.10) and in males 12.7% versus 9.7% (HR 1.34; 95% CI: 0.98-1.85; p = 0.07). Males treated with Absorb BVS were at higher risk for TVF compared to females treated with Absorb BVS (HR 2.06; 95% CI 1.21-3.53; p = 0.007). Definite/probable device thrombosis occurred in females with Absorb BVS versus XIENCE EES in 1.6% versus 1.4% (HR 1.15; 95% CI: 0.26-5.12; p = 0.86) and in males 3.9% versus 0.7% (HR 5.55; 95% CI: 2.11-14.35; p < 0.001). A statistical significant interaction between sex and device was present for TVF (p = 0.02), but was not seen for definite/probable device thrombosis (p = 0.08).

CONCLUSIONS

In this subgroup analysis, Absorb BVS used in routine practice tends to result in better clinical outcomes in females compared to males.

PCI and CABG for Treating Stable Coronary Artery Disease: JACC Review Topic of the Week

Percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) are considered revascularization procedures, but only CABG can prolong life in stable coronary artery disease. Thus, PCI and CABG mechanisms may differ. Viability and/or ischemia detection to guide revascularization have been unable to accurately predict treatment effects of CABG or PCI, questioning a revascularization mechanism for improving survival. By contrast, preventing myocardial infarction may save lives. However, the majority of infarcts are generated by non-flow-limiting stenoses, but PCI is solely focused on treating flow-limiting lesions. Thus, PCI cannot be expected to significantly limit new infarcts, but CABG may do so through providing flow distal to vessel occlusions. All comparisons of CABG to PCI or medical therapy that demonstrate survival effects with CABG also demonstrate infarct reduction. Thus, CABG may differ from PCI by providing "surgical collateralization," prolonging life by preventing myocardial infarctions. The evidence is reviewed here.

Bioresorbable Vascular Scaffolds-Dead End or Still a Rough Diamond?

Percutaneous coronary interventions with stent-based restorations of vessel patency have become the gold standard in the treatment of acute coronary states. Bioresorbable vascular scaffolds (BVS) have been designed to combine the efficiency of drug-eluting stents (DES) at the time of implantation and the advantages of a lack of foreign body afterwards. Complete resolution of the scaffold was intended to enable the restoration of vasomotor function and reduce the risk of device thrombosis. While early reports demonstrated superiority of BVS over DES, larger-scale application and longer observation exposed major concerns about their use, including lower radial strength and higher risk of thrombosis resulting in higher rate of major adverse cardiac events. Further focus on procedural details and research on the second generation of BVS with novel properties did not allow to unequivocally challenge position of DES. Nevertheless, BVS still have a chance to present superiority in distinctive indications. This review presents an outlook on the available first and second generation BVS and a summary of results of clinical trials on their use. It discusses explanations for unfavorable outcomes, proposed enhancement techniques and a potential niche for the use of BVS.

OCT-assessment of scaffold resorption: Analysis of strut intensity by a new resorption index for poly-l-lactic acid bioresorbable vascular scaffolds

BACKGROUND

The aim of this study was to analyze individual differences in resorption of bioresorbable vascular scaffolds (BRS) through optical coherence tomography (OCT) analysis and to identify factors potentially influencing the resorption process.

METHODS

Between April 2016 and July 2017 clinically driven invasive coronary angiography and OCT examinations were performed in 36 patients who had previously been treated with a total of 48 BRS (ABSORB BVS, Abbott Vascular, Santa Clara, CA). For each scaffold, a new BRS-RESORB-INDEX (BRI) was calculated.

RESULTS

The mean time interval since implantation was 789 ± 321 days. In OCT, BRS struts remained detectable in all 48 BRS. Normalized light intensity as a marker for the resorption of BRS struts increased with time in a linear fashion (Spearman Rho: p < .001, correlation coefficient = .90; R² [linear] = .91). Multivariable analysis identified diabetes (BRI of patients with diabetes vs. patients without diabetes: 0.34 ± 0.13 vs. 0.58 ± 0.22; p = .002) and presence of Peri-strut low intensity areas (PSLIA, BRI of 10 patients with PSLIA vs. 26 patients without PSLIA: 0.44 ± 0.21 vs. 0.61 ± 18; p = .027) as independent predictors for a prolonged BRS resorption, whereas the resorption rate in ACS patients (STEMI, NSTEMI, and unstable angina; n = 13) was significantly higher as compared to patients without ACS (0.62 ± 0.17 vs. 0.43 ± 0.24; p = .012).

CONCLUSION

In humans, BRS resorption rate is significantly influenced by numerous factors. Our data suggest that diabetes and PSLIA are associated with a prolonged resorption process, whereas in ACS patients, BRS resorption appears to be significantly faster.

Neoatherosclerosis - Long-Term Assessment of Bioresorbable Vascular Scaffold

Although metallic stents improved the safety and efficacy of percutaneous coronary intervention (PCI), even the latest generation of drug-eluting stents (DES) is still limited by several factors. The limitations of DES are mainly related to the permanent metallic caging in vessel, chronic inflammatory response to the polymer and adverse effects of antiproliferative drug on endothelial tissue, leading to impaired physiological vasomotor response and late stent-related adverse events such as stent thrombosis and neoatherosclerosis. Bioresorbable vascular scaffold (Absorb BVS; Abbott Vascular) was designed to overcome these drawbacks of DES by disappearing from the vessel wall. Absorb BVS, however, was withdrawn from the world market because of increased incidence of scaffold thrombosis compared with DES. Importantly, only very limited long-term post-BVS implantation data are available, especially with regard to neoatherosclerosis, which can lead to very late adverse events even after resorption of the scaffold. Therefore, the goal of this review was to highlight the mid to long term clinical outcomes published to date, and to describe the features of the intimal healing process and neoatherosclerosis in the 5 years following Absorb BVS implantation, mainly based on our previous study. This may provide important information on the pathophysiology of the scaffolded vessel for clinicians, and promote identification of future bioresorbable materials for PCI that will minimize the stimulus for neoatherosclerosis.

Acute and long-term relocation of minimal lumen area after bioresorbable scaffold or metallic stent implantation

AIMS

The aim of this study was to investigate relocation of minimal lumen area (MLA) after implantation of a bioresorbable scaffold (BRS).

METHODS AND RESULTS

In the ABSORB II randomised trial (BRS vs everolimus-eluting stent [EES]), lesions were investigated by serial intravascular ultrasound pre procedure, post procedure, and at three years. MLA relocation was defined as an axial MLA shift of more than 2.4 mm. MLA relocation from post procedure to three years was observed in 163/237 (68.8%) and 75/129 (58.1%) of lesions treated by BRS and EES, respectively (p=0.041). When matching preprocedural MLA site with the same topographical sites post procedure and at three years, BRS showed significant late lumen enlargement and expansive remodelling compensating for significant plaque increase, whereas EES showed significant late lumen narrowing with significant plaque growth not compensated for by expansive remodelling from post procedure to three years. In the multivariate analysis, female gender, previous PCI, BRS implantation, total device length, and maximal pressure (either at device implantation or post-dilatation) were independently associated with MLA relocation from post procedure to three years.

CONCLUSIONS

MLA relocation from post procedure to three years was more frequent in BRS than EES. Late lumen enlargement and expansive vessel remodelling at the preprocedural MLA site was observed in BRS, but not in EES.

Neoatherosclerosis 5 Years After Bioresorbable Vascular Scaffold Implantation

BACKGROUND

Data regarding neoatherosclerosis after everolimus-eluting bioresorbable vascular scaffold (BVS) (ABSORB BVS Rev. 1.1, Abbott Vascular, Santa Clara, California) implantation are limited.

OBJECTIVES

This study investigated the findings of neoatherosclerosis at 5 years after BVS 1.1 implantation by using multi-imaging modalities, including optical coherence tomography (OCT).

METHODS

Patients included in the ABSORB EXTEND (ABSORB EXTEND Clinical Investigation) trial at Shonan Kamakura General Hospital underwent OCT at baseline after the index procedure and at 1 and 5 years. Intimal plaque distributions in the in-scaffold and out-scaffold segments were analyzed.

RESULTS

Twenty patients (22 lesions) with stable angina pectoris were enrolled. The median follow-up duration was 67 months (interquartile range: 65 to 69 months), and the mean age was 69 ± 8 years. Patients with diabetes mellitus (25%) were included. Based on the baseline angiogram, 10 (46%) lesions were type B2/C lesions. At 1 and 5 years of follow-up, significant differences in the prevalence of in-scaffold lipid-laden neointima (17% vs. 61%; p = 0.04), calcification (28% vs. 94%; p < 0.01), neovascularization (6% vs. 78%; p < 0.01), and thin-cap fibroatheroma (0% vs. 22%; p = 0.02) were found. In the out-scaffold segments, no significant difference in the plaque prevalence between 1 and 5 years was noted.

CONCLUSIONS

The occurrence and progression of in-scaffold neoatherosclerosis with luminal narrowing was observed at 5 years after BVS 1.1 implantation. The small size of the current study warrants confirmation in larger study. (ABSORB EXTEND Clinical Investigation [ABSORB EXTEND]; NCT01023789).

Serial Optical Coherence Tomography at Baseline, 7 Days, and 1, 3, 6 and 12 Months After Bioresorbable Scaffold Implantation in a Growing Porcine Model

BACKGROUND

Little is known about serial changes in lumen and device dimensions after bioresorbable scaffold implantation in a growing animal model. Methods and Results: ABSORB (n=14) or bare metal stents (ICROS amg [Abbott Vascular, Santa Clara, CA, USA], Winsen-Luhe, Germany; n=15) were implanted in the coronary arteries of domestic swine (a hybrid of Finnish-Norwegian Landrace swine) weighing 30-35 kg. Angiography and optical coherence tomography (OCT) were performed immediately after implantation and repeated at 7 days, 1, 3, 6 and 12 months after the index procedure. One month after implantation, mean lumen area decreased relative to baseline in both groups (relative area change from baseline, -41.4±15.6% for ABSORB vs. -20.9±18.6% for ICROS) while mean device area decreased only in the ABSORB group (relative area change: -11.1±9.4% vs. +0.14±7.95%, respectively). At 12 months, mean lumen area increased relative to baseline in both groups (relative area change from baseline, +55.6±22.4% vs. +32.3±83.6%, respectively) in accordance with the swine growth weighing up to 260-300 kg. Mean device area in the ICROS group remained stable whereas that in the ABSORB group began to increase between 3 and 6 months along with the vessel growth (relative area change: +107.8±25.7% vs. +0.14±7.95%).

CONCLUSIONS

In the growing porcine model, ABSORB was associated with greater extent of recoil 1 month after implantation compared with ICROS but demonstrated substantial adaptability to vessel growth in late phase.

Undiscovered pathology of transient scaffolding t1remains a driver of failures in clinical trials

AIM

To statistically examine the released clinical trials and meta-analyses of polymeric bioresorbable scaffolds resuming the main accomplishments in the field with a translation to the routine clinical practice.

METHODS

The statistical power in clinical trials such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA, and few meta-analyses by the post hoc odds ratio-based sample size calculation, and the patterns of artery remodeling published in papers from ABSORB A and B trials were evaluated.

RESULTS

The phenomenal admiration from the first ABSORB studies in 2006-2013 was replaced by the tremendous disappointment in 2014-2017 due to reported relatively higher rates of target lesion failure (a mean prevalence of 9.16%) and device thrombosis (2.38%) in randomized controlled trials. Otherwise, bioresorbable vascular scaffold (BVS) performs as well as the metallic drug-eluting stent (DES) with a trend toward some benefits for cardiac mortality [risk ratio (RR), 0.58-0.94, P > 0.05]. The underpowered design was confirmed for some studies such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA trials, and meta-analyses of Polimeni, Collet, and Mahmoud with some unintentional bias (judged by the asymmetrical Funnel plot). Scaffold thrombosis rates with Absorb BRS were comparable with DES performed with a so-called strategy of the BVS implantation with optimized pre-dilation (P), sizing (S) and post-dilation (P) (PSP) implantation (RR, PSP vs no PSP 0.37) achieving 0.35 per 100 patient-years, which is comparable to the RR 0.49 with bare-metal stents and the RR 1.06 with everolimus DES. Both ABSORB II and ABSORB III trials were powered enough for a five-year follow-up, but the results were not entirely conclusive due to the mostly non-significant fashion of data. The powered meta-analyses were built mostly on statistically poor findings.

CONCLUSION

The misunderstanding of the pathology of transient scaffolding drives the failures of the clinical trials. More bench studies of the vascular response are required. Several next-generation BVS including multifunctional electronic scaffold grant cardiology with a huge promise to make BVS technology great again.

Relation between bioresorbable scaffold sizing using QCA-Dmax and long-term clinical outcomes in 1,232 patients from three study cohorts (ABSORB Cohort B, ABSORB EXTEND, and ABSORB II)

AIMS

This study sought to investigate the long-term clinical outcomes related to scaffold sizing based on quantitative coronary angiography.

METHODS AND RESULTS

A total of 1,248 patients who received Absorb bioresorbable scaffolds in the ABSORB Cohort B, ABSORB EXTEND, and ABSORB II trials were included in the analysis. The incidence of MACE (a composite of cardiac death, any myocardial infarction [MI], and ischaemia-driven target lesion revascularisation [ID-TLR]) was analysed according to the Dmax subclassification of oversized scaffold group versus non-oversized (any undersize) scaffold group. At three years, event rates were similar in both groups in MACE (9.4% vs. 9.8%, p=0.847), target vessel MI (5.2% vs. 4.8%, p=0.795), and ID-TLR (4.8% vs. 5.8%, p=0.445). Landmark analysis after one year showed that the non-oversized scaffold group had higher rates of MACE (3.2% vs. 6.9%, log-rank p=0.004), target vessel MI (0.7% vs. 2.7%, log-rank p=0.007), and ID-TLR (2.5% vs. 4.7%, log-rank p=0.041).

CONCLUSIONS

Implantation of an undersized scaffold was associated with a higher risk of MACE between one and three years, while in the previous report an oversized scaffold was associated with a higher risk of MACE up to one year. This implies different mechanisms for early and late events after scaffold implantation.

Polymeric endovascular strut and lumen detection algorithm for intracoronary optical coherence tomography images

Polymeric endovascular implants are the next step in minimally invasive vascular interventions. As an alternative to traditional metallic drug-eluting stents, these often-erodible scaffolds present opportunities and challenges for patients and clinicians. Theoretically, as they resorb and are absorbed over time, they obviate the long-term complications of permanent implants, but in the short-term visualization and therefore positioning is problematic. Polymeric scaffolds can only be fully imaged using optical coherence tomography (OCT) imaging-they are relatively invisible via angiography-and segmentation of polymeric struts in OCT images is performed manually, a laborious and intractable procedure for large datasets. Traditional lumen detection methods using implant struts as boundary limits fail in images with polymeric implants. Therefore, it is necessary to develop an automated method to detect polymeric struts and luminal borders in OCT images; we present such a fully automated algorithm. Accuracy was validated using expert annotations on 1140 OCT images with a positive predictive value of 0.93 for strut detection and an R2 correlation coefficient of 0.94 between detected and expert-annotated lumen areas. The proposed algorithm allows for rapid, accurate, and automated detection of polymeric struts and the luminal border in OCT images.

Coronary calcification as a mechanism of plaque/media shrinkage in vessels treated with bioresorbable vascular scaffold: A multimodality intracoronary imaging study

BACKGROUND AND AIMS

Whether coronary calcification is correlated with plaque/media shrinkage (PS) remains unclear. The aim of this study was to assess the relationship between the calcification process and PS, combining serial optical coherence tomography (OCT) and intravascular ultrasound (IVUS) in vessels treated with bioresorbable vascular scaffolds (BVS).

METHODS

In 15 patients (16 vessels), OCT and IVUS images were matched using anatomic landmarks at post-procedure and five years. PS was defined as relative decrease in plaque/media area >5%. The association between the calcification process and PS was investigated. Mixed effect models were used to assess correlations and changes over time.

RESULTS

Seventy-two OCT and IVUS paired cross sections in- and out-scaffolded segments were matched at baseline and follow-up (432 images). In total, 35 out of the 72 cross sections showed PS, and 37 cross sections showed no PS (non-PS) at 5-year follow-up. Delta (Δ) plaque/media area showed negative correlation with Δ OCT calcium area (r = -0.29, p = 0.004), Δ OCT calcium arc (r = -0.42, p < 0.001), Δ OCT calcium length (r = -0.5, p < 0.001), and Δ IVUS calcium arc (r = -0.31, p = 0.024), respectively. On echogenicity analysis, Δ plaque/media area was positively associated with Δ hypoechogenic area (r = 0.47, p = 0.002). An increase in calcium area was negatively correlated to Δ hypoechogenicity (r = -0.29, p < 0.016). The increase in calcium area was positively correlated with Δ lumen area (r = 0.24, p = 0.044).

CONCLUSIONS

In segments treated with BVS, the calcification process was associated with PS, decrease in the hypoechogenic tissue and late luminal enlargement. Combining IVUS and OCT provides a unique method to assess the correlation between the calcification process and plaque/media shrinkage.

Bioresorbable Vascular Scaffold Korean Expert Panel Report

Bioresorbable vascular scaffold (BRS) is an innovative device that provides structural support and drug release to prevent early recoil or restenosis, and then degrades into nontoxic compounds to avoid late complications related with metallic drug-eluting stents (DESs). BRS has several putative advantages. However, recent randomized trials and registry studies raised clinical concerns about the safety and efficacy of first generation BRS. In addition, the general guidance for the optimal practice with BRS has not been suggested due to limited long-term clinical data in Korea. To address the safety and efficacy of BRS, we reviewed the clinical evidence of BRS implantation, and suggested the appropriate criteria for patient and lesion selection, scaffold implantation technique, and management.

Effect of Technique on Outcomes Following Bioresorbable Vascular Scaffold Implantation: Analysis From the ABSORB Trials

BACKGROUND

Procedural technique may affect clinical outcomes after bioresorbable vascular scaffold (BVS) implantation. Prior studies suggesting such a relationship have not adjusted for baseline patient and lesion characteristics that may have influenced operator choice of technique and outcomes.

OBJECTIVES

This study sought to determine whether target lesion failure (TLF) (cardiac death, target-vessel myocardial infarction, or ischemia-driven target lesion revascularization) and scaffold thrombosis (ScT) rates within 3 years of BVS implantation are affected by operator technique (vessel size selection and pre- and post-dilation parameters).

METHODS

TLF and ScT rates were determined in 2,973 patients with 3,149 BVS-treated coronary artery lesions from 5 prospective studies (ABSORB II, ABSORB China, ABSORB Japan, ABSORB III, and ABSORB Extend). Outcomes through 3 years (and between 0 to 1 and 1 to 3 years) were assessed according to pre-specified definitions of optimal technique (pre-dilation, vessel sizing, and post-dilation). Multivariable analysis was used to adjust for differences in up to 18 patient and lesion characteristics.

RESULTS

Optimal pre-dilation (balloon to core laboratory-derived reference vessel diameter ratio ≥1:1), vessel size selection (reference vessel diameter ≥2.25 mm and ≤3.75 mm), and post-dilation (with a noncompliant balloon at ≥18 atm and larger than the nominal scaffold diameter, but not by >0.5 mm larger) in all BVS-treated lesions were performed in 59.2%, 81.6%, and 12.4% of patients, respectively. BVS implantation in properly sized vessels was an independent predictor of freedom from TLF through 1 year (hazard ratio [HR]: 0.67; p = 0.01) and through 3 years (HR: 0.72; p = 0.01), and of freedom from ScT through 1 year (HR: 0.36; p = 0.004). Aggressive pre-dilation was an independent predictor of freedom from ScT between 1 and 3 years (HR: 0.44; p = 0.03), and optimal post-dilation was an independent predictor of freedom from TLF between 1 and 3 years (HR: 0.55; p = 0.05).

CONCLUSIONS

In the present large-scale analysis from the major ABSORB studies, after multivariable adjustment for baseline patient and lesion characteristics, vessel sizing and operator technique were strongly associated with BVS-related outcomes during 3-year follow-up. (ABSORB II Randomized Controlled Trial [ABSORB II]; NCT01425281; ABSORB III Randomized Controlled Trial [RCT] [ABSORB-III]; NCT01751906; A Clinical Evaluation of Absorb Bioresorbable Vascular Scaffold [Absorb BVS] System in Chinese Population-ABSORB CHINA Randomized Controlled Trial [RCT] [ABSORB CHINA]; NCT01923740; ABSORB EXTEND Clinical Investigation [ABSORB EXTEND]; NCT01023789; AVJ-301 Clinical Trial: A Clinical Evaluation of AVJ-301 [Absorb BVS] in Japanese Population [ABSORB JAPAN]; NCT01844284).