Incidence and imaging outcomes of acute scaffold disruption and late structural discontinuity after implantation of the absorb Everolimus-Eluting fully bioresorbable vascular scaffold: optical coherence tomography assessment in the ABSORB cohort B Trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions). JACC Cardiovasc Interv. 2014;7:1400-1411. [PMID: 25523532 DOI: 10.1016/j.jcin.2014.06.016]

Current situation and overview of resorbable magnesium scaffolds: a perspective for overcoming the remaining issues of polymeric bioresorbable scaffold

Bioresorbable scaffolds (BRS) were developed as an innovative solution to overcome the limitations of metallic stents. While polymeric BRS initially demonstrated comparable clinical outcomes to drug-eluting stent (DES) in clinical trials, subsequent large-scale studies revealed that patients implanted with polymeric BRS experienced higher rates of scaffold thrombosis (ScT) and target lesion failure compared to those with metallic stents. Resorbable magnesium scaffolds (RMS) have emerged as a promising alternative owing to magnesium's natural degradability and favorable mechanical properties. Learning from the mechanism of polymeric BRS failure and through continuous improvements, recent clinical trials have shown promising clinical performance for RMS technology. However, comparative studies between RMS and DES have continued to highlight the remaining challenges with RMS, particularly in regard to late lumen loss. Recent advancements in third-generation RMS show improvements in strut thickness and homogeneous degradation, which enhances sustained structural integrity throughout the degradation process. Based on encouraging results from a first-in-human trial of the latest version of RMS, a randomized controlled trial has been initiated to compare the outcomes between metallic stents and the latest RMS, with patient enrollment already underway. This review aims to explore the limitations of polymeric BRS and provide an overview of the current developments and future potential of magnesium-based BRS.

Safety and Efficacy of Everolimus-Eluting Bioresorbable Vascular Scaffold Versus Second-Generation Drug-Eluting Stents in Real-World Practice

BACKGROUND

The risk of device thrombosis and device-oriented clinical outcomes with bioresorbable vascular scaffold (BVS) was reported to be significantly higher than with contemporary drug-eluting stents (DESs). However, optimal device implantation may improve clinical outcomes in patients receiving BVS. The current study evaluated mid-term safety and efficacy of Absorb BVS with meticulous device optimization under intravascular imaging guidance.

METHODS

The SMART-REWARD and PERSPECTIVE-PCI registries in Korea prospectively enrolled 390 patients with BVS and 675 patients with DES, respectively. The primary endpoint was target vessel failure (TVF) at 2 years and the secondary major endpoint was patient-oriented composite outcome (POCO) at 2 years.

RESULTS

Patient-level pooled analysis evaluated 1,003 patients (377 patients with BVS and 626 patients with DES). Mean scaffold diameter per lesion was 3.24 ± 0.30 mm in BVS group. Most BVSs were implanted with pre-dilatation (90.9%), intravascular imaging guidance (74.9%), and post-dilatation (73.1%) at proximal to mid segment (81.9%) in target vessel. Patients treated with BVS showed comparable risks of 2-year TVF (2.9% vs. 3.7%, adjusted hazard ratio [HR], 1.283, 95% confidence interval [CI], 0.487-3.378, P = 0.615) and 2-year POCO (4.5% vs. 5.9%, adjusted HR, 1.413, 95% CI, 0.663-3.012, P = 0.370) than those with DES. The rate of 2-year definite or probable device thrombosis (0.3% vs. 0.5%, P = 0.424) was also similar. The sensitivity analyses consistently showed comparable risk of TVF and POCO between the 2 groups.

CONCLUSION

With meticulous device optimization under imaging guidance and avoidance of implantation in small vessels, BVS showed comparable risks of 2-year TVF and device thrombosis with DES.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02601404, NCT04265443.

Bioresorbable scaffolds vs. drug-eluting stents for patients with myocardial infarction: A systematic review and meta-analysis of randomized clinical trials

Objective

To compare the efficacy and safety of bioresorbable scaffolds (BRS) with drug-eluting stents (DES) in patients with myocardial infarction undergoing percutaneous coronary interventions (PCI).

Methods

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing BRS with DES on clinical outcomes with at least 12 months follow-up. Electronic databases of PubMed, CENTRAL, EMBASE, and Web of Science from inception to 1 March 2022 were systematically searched to identify relevant studies. The primary outcome of this study was the device-oriented composite endpoint (DOCE) consisting of cardiac death, target-vessel myocardial infarction, and target lesion revascularization. Secondary outcomes were a composite of major adverse cardiac events (MACE, all-cause death, target-vessel myocardial infarction, or target vessel revascularization) and the patient-oriented composite endpoint (POCE, defined as a composite of all-cause death, myocardial infarction, or revascularization). The safety outcomes were definite/probable device thrombosis and adverse events.

Results

Four randomized clinical trials including 803 participants with a mean age of 60.5 ± 10.8 years were included in this analysis. Patients treated with BRS had a higher risk of the DOCE (RR 1.62, 95% CI: 1.02–2.57, P = 0.04) and MACE (RR 1.77, 95% CI: 1.02–3.08, P = 0.04) compared with patients treated with DES. No significant difference on the POCE (RR 1.33, 95% CI: 0.89–1.98, P = 0.16) and the definite/probable device thrombosis (RR 1.31, 95% CI: 0.46–3.77, P = 0.61) were observed between BRS and DES. No treatment-related serious adverse events were reported.

Conclusion

BRS was associated with a higher risk of DOCE and MACE compared with DES in patients undergoing PCI for myocardial infarction. Although this seems less effective in preventing DOCE, BRS appears as safe as DES.

Systematic review registration

[https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=321501], identifier [CRD 42022321501].

Polymer–Metal Composite Healthcare Materials: From Nano to Device Scale

Metals have been investigated as biomaterials for a wide range of medical applications. At nanoscale, some metals, such as gold nanoparticles, exhibit plasmonics, which have motivated researchers’ focus on biosensor development. At the device level, some metals, such as titanium, exhibit good physical properties, which could allow them to act as biomedical implants for physical support. Despite these attractive features, the non-specific delivery of metallic nanoparticles and poor tissue–device compatibility have greatly limited their performance. This review aims to illustrate the interplay between polymers and metals, and to highlight the pivotal role of polymer–metal composite/nanocomposite healthcare materials in different biomedical applications. Here, we revisit the recent plasmonic engineered platforms for biomolecules detection in cell-free samples and highlight updated nanocomposite design for (1) intracellular RNA detection, (2) photothermal therapy, and (3) nanomedicine for neurodegenerative diseases, as selected significant live cell–interactive biomedical applications. At the device scale, the rational design of polymer–metallic medical devices is of importance for dental and cardiovascular implantation to overcome the poor physical load transfer between tissues and devices, as well as implant compatibility under a dynamic fluidic environment, respectively. Finally, we conclude the treatment of these innovative polymer–metal biomedical composite designs and provide a future perspective on the aforementioned research areas.

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.

Two-stage degradation and novel functional endothelium characteristics of a 3-D printed bioresorbable scaffold

Bioresorbable scaffolds have emerged as a new generation of vascular implants for the treatment of atherosclerosis, and designed to provide a temporary scaffold that is subsequently absorbed by blood vessels over time. Presently, there is insufficient data on the biological and mechanical responses of blood vessels accompanied by bioresorbable scaffolds (BRS) degradation. Therefore, it is necessary to investigate the inflexion point of degradation, the response of blood vessels, and the pathophysiological process of vascular, as results of such studies will be of great value for the design of next generation of BRS. In this study, abdominal aortas of SD rats were received 3-D printed poly-l-actide vascular scaffolds (PLS) for various durations up to 12 months. The response of PLS implanted aorta went through two distinct processes: (1) the neointima with desirable barrier function was obtained in 1 month, accompanied with slow degradation, inflammation, and intimal hyperplasia; (2) significant degradation occurred from 6 months, accompanied with decreasing inflammation and intimal hyperplasia, while the extracellular matrix recovered to normal vessels which indicate the positive remodeling. These in vivo results indicate that 6 months is a key turning point. This “two-stage degradation and vascular characteristics” is proposed to elucidate the long-term effects of PLS on vascular repair and demonstrated the potential of PLS in promoting endothelium function and positive remodeling, which highlights the benefits of PLS and shed some light in the future researches, such as drug combination coatings design.

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Proposed two-stage degradation of a PLLA BRS to reveal distinct neointimal recovery and vascular responsive processes.

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Revealed novel benefits of BRS, including fine endothelium function, anti-thrombosis, and anti-inflammatory.

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Drug combination coatings should be designed concerning special degradation of BRS and the key turning point, 6 months.

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).

Numerical study to identify the effect of fluid presence on the mechanical behavior of the stents during coronary stent expansion

In this study, structural analysis and one-way fluid-structure interaction (FSI) analysis were performed to identify the effect of fluid presence on the mechanical behavior of the stents during stent expansion. An idealized vessel model with stenosis was used for simulation, and stents made of metal and polymer were assumed, respectively. The bilinear model was applied to the stents, and the Mooney-Rivlin model was applied to the arterial wall and plaque. The blood used in the FSI analysis was assumed to be a non-Newtonian fluid. As a result of all numerical simulations, the von Mises stress, the first principal stress and the displacement were calculated as the mechanical behaviors. Through the comparison of the results of the structural analysis with those of the one-way FSI analysis, our results indicated the fluid had no significant influence on the expansion of the metal stent. However, it was found that the expansion of the polymer stent affected by the presence of fluid. These findings meant the one-way FSI technique was suggested to achieve an accurate analysis when targeting a polymer stent for numerical simulation.

Intracoronary Injection of Autologous CD34+ Cells Improves One-Year Left Ventricular Systolic Function in Patients with Diffuse Coronary Artery Disease and Preserved Cardiac Performance-A Randomized, Open-Label, Controlled Phase II Clinical Trial

This phase II randomized controlled trial tested whether intracoronary autologous CD34+ cell therapy could further improve left ventricular (LV) systolic function in patients with diffuse coronary artery disease (CAD) with relatively preserved LV ejection fraction (defined as LVEF >40%) unsuitable for coronary intervention. Between December 2013 and November 2017, 60 consecutive patients were randomly allocated into group 1 (CD34+ cells, 3.0 × 10⁷/vessel/n = 30) and group 2 (optimal medical therapy; n = 30). All patients were followed for one year, and preclinical and clinical parameters were compared between two groups. Three-dimensional echocardiography demonstrated no significant difference in LVEF between groups 1 and 2 (54.9% vs. 51.0%, respectively, p = 0.295) at 12 months. However, compared with baseline, 12-month LVEF was significantly increased in group 1 (p < 0.001) but not in group 2 (p = 0.297). From baseline, there were gradual increases in LVEF in group 1 compared to those in group 2 at 1-month, 3-months, 6-months and 12 months (+1.6%, +2.2%, +2.9% and +4.6% in the group 1 vs. −1.6%, −1.5%, −1.4% and −0.9% in the group 2; all p < 0.05). Additionally, one-year angiogenesis (2.8 ± 0.9 vs. 1.3 ± 1.1), angina (0.4 ± 0.8 vs. 1.8 ± 0.9) and HF (0.7 ± 0.8 vs. 1.8 ± 0.6) scores were significantly improved in group 1 compared to those in group 2 (all p < 0.001). In conclusion, autologous CD34+ cell therapy gradually and effectively improved LV systolic function in patients with diffuse CAD and preserved LVEF who were non-candidates for coronary intervention (Trial registration: ISRCTN26002902 on the website of ISRCTN registry).

Bioresorbable vascular stents and drug-eluting stents in treatment of coronary heart disease: a meta-analysis

OBJECTIVE

To compare the efficacy and safety of bioresorbable vascular stents (BVS) and drug-eluting stents (DES) in coronary heart disease.

METHODS

The full text of clinical studies involving BVS and DES was retrieved in PubMed, Springer, EMBASE, Wiley-Blackwell, and Chinese Journal Full-text Database. Review Manager 5.3 was used for meta-analysis to evaluate the risk of target lesion failure, stent thrombosis and cardiac death in BVS and DES.

RESULTS

Finally, 10 studies with 6383 patients were included in the meta-analysis. Compared with DES group, BVS group had significantly increased risk of target lesion failure (OR = 1.46, 95%CI 1.20-1.79, P = 0.0002; P _{Heterogeneity} = 0.68, I² = 0%), stent thrombosis (OR = 2.70, 95%CI 1.57-4.66, P = 0.0003; P _{Heterogeneity} = 1.00, I² = 0%) and cardiac death (OR = 2.19, 95%CI 1.17-4.07, P = 0.01; P _{Heterogeneity} = 0.93, I² = 0%).

CONCLUSION

This study shows that DES is a safer treatment than BVS for coronary revascularization.

Optical Coherence Tomography for Coronary Bioresorbable Vascular Scaffold Implantation: A Randomized Controlled Trial

BACKGROUND

We investigated whether optical coherence tomography (OCT) guidance would reduce nonoptimal bioresorbable vascular scaffold (BVS) deployment.

METHODS

This was a randomized controlled trial. Patients who required percutaneous coronary intervention for ischemic heart disease were recruited from 2 centers in Korea. The enrolled patients were randomly assigned to receive either OCT-guided BVS (Absorb; Abbott Vascular) implantation or angiography-guided BVS implantation using an optimized technique. The primary outcome was nonoptimal deployment, which was a composite outcome of the following parameters assessed by OCT: a minimal scaffold area <5 mm², residual area stenosis >20%, incomplete apposition of the scaffold struts >5%, major edge dissection, or scaffold disruption. The secondary outcome was a procedural complication defined by the occurrence of no reflow, coronary perforation, or flow-limiting dissection.

RESULTS

Between September 2016 and January 2018, 88 patients (90 lesions) were assigned to OCT guidance, while 88 patients (89 lesions) were assigned to angiography guidance. The recruitment was prematurely terminated in March 2018 because the manufacturer stopped supplying BVS. Postprocedural OCT data were available for 88 lesions with OCT guidance and for 88 lesions with angiography guidance. There was nonoptimal BVS deployment postprocedurally in 35.2% of patients in the OCT-guidance group and in 38.6% in the angiography-guidance group (absolute difference, -3.7% [95% CI, -19.0% to 11.6%]; P=0.64). There were no procedural complications in either group.

CONCLUSIONS

OCT-guided BVS implantation did not reduce the incidence of nonoptimal deployment compared to that of angiography-guided BVS implantation (using optimized techniques).

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02894697.

First-in-man study of a thinner-strut sirolimus-eluting bioresorbable scaffold (FUTURE-I): Three-year clinical and imaging outcomes

OBJECTIVES

The FUTURE-I study aimed to assess preliminary safety and effectiveness with the long-term clinical and imaging follow-up for the Firesorb (MicroPort, Shanghai, China), a thinner-strut sirolimus-eluting bioresorbable scaffold (BRS).

BACKGROUND

First-generation BRS has been associated with unexpected device-related adverse outcomes at long-term follow-up.

METHODS

In this prospective, open-label, first-in-man study, patients with single de novo lesions in native coronary arteries were randomized 2:1 into two cohorts after successful Firesorb implantation: cohort 1 (n = 30) underwent multimodality imaging assessment at 6 and 24 months; and cohort 2 (n = 15) at 12 and 36 months. All patients underwent clinical follow-up at 1, 6, and 12 months and annually up to 5 years.

RESULTS

Between January and March 2016, 45 patients were enrolled. At 3-year follow-up, one patient had experienced target lesion failure and none scaffold thrombosis. In-scaffold minimal lumen diameter decreased significantly from 6-month to 2-year (2.53 ± 0.24 mm vs. 2.27 ± 0.37 mm, p = .0003), and only numerically from 1-year to 3-year follow-up (2.48 ± 0.28 mm vs. 2.22 ± 0.13 mm, p = .08). By optical coherence tomography, neointimal strut coverage at 3-year follow-up was 99.8%, and very low rate of late scaffold discontinuity was observed, only in one patient on two cross sections with three malapposed struts.

CONCLUSIONS

At 3-year follow-up of the FUTURE-I study, implantation of the thinner-strut Firesorb BRS appeared preliminary feasible and effective in the treatment of patients with noncomplex coronary lesions.

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.

Everolimus-eluting bioresorbable vascular scaffolds: learning from the past to improve the future

Bioresorbable vascular scaffolds (BVS) were developed to overcome the long-term limitations of metallic drug-eluting stents (DES). Shortcomings of DES include their permanent metallic cage which prevents normal coronary vasomotion, vascular remodeling, precludes future bypass grafting, and creates a nidus for very late stent thrombosis. With its transient scaffold which provides early mechanical support and subsequently resorbs thereby restoring physiologic properties and architecture of the vasculature, BVS offers a promising development within the field of interventional cardiology. Even though various BVS have been or are currently under development, the ABSORB BVS from Abbott Vascular was the first FDA approved device. In this review, we shed light on shortcomings of the current generation DES and theoretical advantages of BVS. In addition, we will discuss in detail clinical data from observational studies, meta-analyses, registries, and randomized controlled trials as it pertains to the efficacy and safety outcomes with everolimus-eluting BVS as compared to the current generation everolimus-eluting metallic stents (EES). We will summarize reasons behind the disappointing results from clinical trials and the failure of first generation BVS leading to its withdrawal from the market. Lastly, we will briefly review ongoing developments with the newer-generation BVS and future pre-clinical and clinical studies that are underway to evaluate the efficacy and safety of second-generation BVS.

Impact of Absorb bioresorbable scaffold implantation technique on post-procedural quantitative coronary angiographic endpoints in ST-elevation myocardial infarction: a sub-analysis of the BVS STEMI STRATEGY-IT study

AIMS

The aim of the study was to evaluate the impact of bioresorbable vascular scaffold (BRS) implantation technique on post-procedural quantitative coronary angiography (QCA) parameters in ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

We assessed 442 STEMI patients who underwent BRS implantation in the BVS STEMI STRATEGY-IT study. Optimal BRS implantation was assessed using the PSP score, developed and validated in the GHOST-EU registry. We analysed post-implantation QCA parameters, including minimum lumen diameter (MLD) and maximum footprint, in patients with and without optimal BRS implantation, coded as maximum PSP score. Patients with optimal BRS implantation had higher post-procedural MLD and lower maximum footprint than those without. Multivariate analysis demonstrated that optimal BRS implantation was an independent predictor of high post-procedural MLD, defined as ≥2.4 mm for 2.5 or 3.0 mm BRS and ≥2.8 mm for 3.5 mm BRS. Thrombectomy before optimal BRS implantation showed a trend towards higher post-procedural MLD and lower maximum footprint. There was no relationship between optimal BRS implantation and device-oriented composite events at one year.

CONCLUSIONS

Optimal BRS implantation, as assessed by PSP score, was associated with better post-procedural QCA parameters in STEMI. Thrombectomy before optimal BRS implantation might improve angiographic results in STEMI. Long-term follow-up is needed to analyse the relationship between QCA parameters and clinical outcomes after BRS implantation in STEMI patients.

Bioresorbable Scaffold for Treatment of Coronary Artery Lesions: Intravascular Ultrasound Results From the ABSORB Japan Trial

OBJECTIVES

The aim of this study was to characterize post-procedural intravascular ultrasound (IVUS) findings in the ABSORB Japan trial, specifically stratified by the size of target coronary arteries.

BACKGROUND

Despite overall noninferiority confirmed in recent randomized trials comparing bioresorbable vascular scaffolds (BVS) (Absorb BVS) and cobalt-chromium everolimus-eluting metallic stents (CoCr-EES), higher event rates of Absorb BVS have been reported with suboptimal deployment, especially in small coronary arteries.

METHODS

In the ABSORB Japan trial, 150 patients (2:1 randomization) were scheduled in the IVUS cohort. Small vessel was defined as mean reference lumen diameter <2.75 mm. Tapered-vessel lesions were defined as tapering index (proximal/distal reference lumen diameter) ≥1.2.

RESULTS

Overall, IVUS revealed that the Absorb BVS arm had smaller device expansion than the CoCr-EES arm did, which was particularly prominent in small- and tapered-vessel lesions. Higher tapering index was also associated with higher rates of incomplete strut apposition in Absorb BVS, but not in CoCr-EES. With respect to procedural techniques, small-vessel lesions were treated more frequently with noncompliant balloons at post-dilatation but using significantly lower pressure in the Absorb BVS arm. In contrast, tapered-vessel lesions were post-dilated at equivalent pressure but with significantly smaller balloon catheters in the Absorb BVS arm, compared with the CoCr-EES arm.

CONCLUSIONS

The significantly smaller device expansion especially in small vessels may account for the poorer outcomes of Absorb BVS in this lesion type. Appropriate optimization strategy, possibly different between polymeric and metallic devices, needs to be established for bioresorbable scaffold technology. (AVJ-301 Clinical Trial: A Clinical Evaluation of AVJ-301 Absorb™ BVS) in Japanese Population [ABSORB JAPAN]; NCT01844284).

Absorb Bioresorbable Scaffold Versus Xience Metallic Stent for Prevention of Restenosis Following Percutaneous Coronary Intervention in Patients at High Risk of Restenosis: Rationale and Design of the COMPARE ABSORB Trial

BACKGROUND

The advent of bioresorbable vascular scaffolds (BVS) was considered as a potential improvement in percutaneous coronary intervention (PCI) after the groundbreaking development of drug eluting stents (DES). However, the clinical performance, long-term safety and efficacy of BVS in complex coronary lesions remain uncertain. COMPARE ABSORB, a multicenter, single blind, prospective randomized trial, aims to compare the clinical outcomes between the Absorb BVS and Xience everolimus-eluting metallic stent (EES) in patients with coronary artery disease and a high risk of restenosis.

DESIGN

COMPARE ABSORB is designed to enroll 2100 patients at up to 45 European sites. Enrolled patients will possess high risk for restenosis due to clinical profile or coronary lesion complexity and will undergo elective or emergent PCI. Once included in the study, patients will receive either Absorb BVS or Xience EES. Specific advice on implantation technique including mandatory pre-dilatation, sizing and post-dilatation (PSP), will be used in the Absorb BVS arm. The primary endpoint is target lesion failure (TLF), a device-oriented composite endpoint (cardiac death, target vessel myocardial infarction and clinically-indicated target lesion revascularization). The trial is powered to assess non-inferiority of Absorb BVS compared with Xience EES with a predetermined non-inferiority margin of 4.5% at 1 year after index procedure. The clinical follow-up will continue for 7 years.

CONCLUSIONS

The prospective COMPARE ABSORB randomized trial (ClinicalTrials.govNCT02486068) will help to assess the long-term safety and efficacy of Absorb BVS compared with Xience EES in the treatments of patients with complex coronary artery disease and a high attendant risk of restenosis.

Intracoronary Optical Coherence Tomography 2018: Current Status and Future Directions

The advent of intravascular imaging has been a significant advancement in visualization of coronary arteries, particularly with optical coherence tomography (OCT) that allows for high-resolution imaging of intraluminal and transmural coronary structures. Accumulating data support a clinical role for OCT in a multitude of clinical scenarios, including assessing the natural history of atherosclerosis and modulating effects of therapies, mechanisms of acute coronary syndromes, mechanistic insights into the effects of novel interventional devices, and optimization of percutaneous coronary intervention. In this state-of-the-art review, we provide an overview of the published data on the clinical utility of OCT, highlighting the areas that need further investigation and the current barriers for further adoption of OCT in interventional cardiology practice.

The relationship of pre-procedural Dmax based sizing to lesion level outcomes in Absorb BVS and Xience EES treated patients in the AIDA trial

Due to expansion limits of the Absorb bioresorbable scaffold a meticulous implantation with correct sizing is required. We sought to investigate the clinical outcomes based on the sizing of the device related to the maximal lumen diameter measured by quantitative coronary angiography in Absorb BVS and Xience EES treated lesions in the AIDA trial. Sizing of Absorb bioresorbable vascular scaffold (BVS) and Xience everolimus eluting stent (EES) was graded according to the definitions of device non-oversize and device oversize on pre-procedural angiography. Lesion-oriented outcomes (LOCE) (device thrombosis, TLR and TVMI) that occurred during 2 years follow-up were related to device non-oversized or oversized status. In the Absorb BVS group, LOCE occurred in 48 (7.4%) lesions in the oversized group and in 32 (8.2%) lesions in the non-oversized group (HR 0.91; 95% CI 0.58-1.42; p = 0.681), whereas TLR occurred in 34 (5.3%) lesions and in 23 lesions (5.9%), respectively (HR 0.89; 95% CI 0.52-1.51; p = 0.666). Definite scaffold thrombosis occurred in 11 (1.7%) device oversized treated lesions against 16 (4.1%) device non-oversized treated lesions (HR 0.41; 95% CI 0.19-0.89; p = 0.020). There were no differences in event rates between oversized and non-oversized groups in lesions treated with Xience EES. There was no significant difference in LOCE between oversized and non-oversized treated Absorb BVS and Xience EES treated lesions. Non-oversized Absorb BVS implantation was associated with a higher risk of scaffold thrombosis at complete 2 years follow-up. The majority of very late scaffold thrombosis occurred in properly sized devices.

Mechanical performance and healing patterns of the novel sirolimus-eluting bioresorbable Fantom scaffold: 6-month and 9-month follow-up by optical coherence tomography in the FANTOM II study

Objectives

We aimed to evaluate the mechanical properties and healing patterns 6 and 9 months after implantation of the sirolimus-eluting Fantom bioresorbable scaffold (BRS).

Background

The Fantom BRS (Reva Medical, San Diego, USA) has differentiating properties including radiopacity, strut thickness of 125 µm, high expansion capacity and has demonstrated favourable mid-term clinical and angiographic outcomes.

Methods and results

FANTOM II was a prospective, single arm study with implantation of the Fantom BRS in 240 patients with stable angina pectoris. Guidance by optical coherence tomography (OCT) was encouraged and was repeated at 6-month (cohort A) or 9-month follow-up (cohort B). Matched baseline and follow-up OCT recordings were available in 152 patients. In-scaffold mean lumen area in cohort A was 6.8±1.7 mm² and 5.7±1.4 mm² at baseline and follow-up (p<0.0001) and was 7.2±1.6 mm² and 5.6±1.4 mm² in cohort B (p<0.0001). Mean scaffold area remained stable from 7.1±1.5 mm² at baseline to 7.2±1.4 mm² at 6 months (p=0.12), and from 7.4±1.5 mm² to 7.3±1.4 mm² at 9 months. Strut malapposition was median 0.8 (IQR 0.0;3.5)% and 1.8 (IQR 0.3;6.0)% at baseline and was 0.0 (IQR 0.0;0.0)% in both groups at 6-month and 9-month follow-up. Strut tissue coverage was 98.1 (IQR 95.9;99.4)% at 6 months and 98.9 (IQR 98.3;100.0)% at 9 months.

Conclusions

The novel Fantom BRS had favourable healing patterns at 6-month and 9-month follow-up as malapposition was effectively resolved and strut coverage was almost complete. The scaffold remained stable through follow-up with no signs of systematic late recoil.

Device specificity of vascular healing following implantation of bioresorbable vascular scaffolds and bioabsorbable polymer metallic drug-eluting stents in human coronary arteries: the ESTROFA OCT BVS vs. BP-DES study

AIMS

We sought to compare vascular healing with bioresorbable everolimus-eluting vascular scaffolds (BVS) and drug-eluting stents with bioabsorbable polymers (BP-DES) at six and 12 months both implanted in the same patients.

METHODS AND RESULTS

This was a multicentre and prospective study including patients with at least two comparable lesions to treat. In every patient both BVS and BP-DES (SYNERGY, Orsiro or BioMatrix Flex) were implanted by lesion randomisation. Patients included were evaluated with optical coherence tomography at six or 12 months (2:1). Finally, 68 patients had an examination at six months and 27 patients at 12 months. The rates of uncovered struts at six months were 1.7±3.2% for BVS and 5.3±5.6% for BP-DES (p=0.0001), and at 12 months 0.48±0.72% and 4.8±5%, respectively (p=0.001). Rates of strut malapposition were significantly lower with BVS. There was no significant intra-patient correlation with BP-DES/BVS for endpoints. Evaginations were more frequent and larger with BVS. Discontinuities in BVS were observed in 19.4% at six months and 14.3% at 12 months.

CONCLUSIONS

Vascular healing with BVS and BP-DES could be more device-specific than patient-specific. At follow-up, BVS presented fewer uncovered or non-apposed struts than BP-DES but more frequent and larger evaginations. Discontinuities in BVS were relatively frequent at both time points.

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.

Understanding the Impact of Stent and Scaffold Material and Strut Design on Coronary Artery Thrombosis from the Basic and Clinical Points of View

The technology of percutaneous coronary intervention (PCI) is constantly being refined in order to overcome the shortcomings of present day technologies. Even though current generation metallic drug-eluting stents (DES) perform very well in the short-term, concerns still exist about their long-term efficacy. Late clinical complications including late stent thrombosis (ST), restenosis, and neoatherosclerosis still exist and many of these events may be attributed to either the metallic platform and/or the drug and polymer left behind in the arterial wall. To overcome this limitation, the concept of totally bioresorbable vascular scaffolds (BRS) was invented with the idea that by eliminating long-term exposure of the vessel wall to the metal backbone, drug, and polymer, late outcomes would improve. The Absorb-bioabsorbable vascular scaffold (Absorb-BVS) represented the most advanced attempt to make such a device, with thicker struts, greater vessel surface area coverage and less radial force versus contemporary DES. Unfortunately, almost one year after its initial approval by the U.S. Food and Drug Administration, this scaffold was withdrawn from the market due to declining devise utilization driven by the concerns about scaffold thrombosis (ScT) seen in both early and late time points. Additionally, the specific causes of ScT have not yet been fully elucidated. In this review, we discuss the platform, vascular response, and clinical data of past and current metallic coronary stents with the Absorb-BVS and newer generation BRS, concentrating on their material/design and the mechanisms of thrombotic complications from the pre-clinical, pathologic, and clinical viewpoints.

Effect of Post-Dilatation Following Primary PCI With Everolimus-Eluting Bioresorbable Scaffold Versus Everolimus-Eluting Metallic Stent Implantation: An Angiographic and Optical Coherence Tomography TROFI II Substudy

OBJECTIVES

This study sought to investigate the effect of post-dilatation on angiographic and intracoronary imaging parameters in the setting of primary percutaneous coronary intervention comparing the everolimus-eluting bioresorbable scaffold (BRS) with the everolimus-eluting metallic stent (EES).

BACKGROUND

Routine post-dilatation of BRS has been suggested to improve post-procedural angiographic and subsequent device-related clinical outcomes.

METHODS

In the ABSORB STEMI TROFI II trial, 191 patients with ST-segment elevation myocardial infarction were randomly assigned to treatment with BRS (n = 95) or EES (n = 96). Minimal lumen area and healing score as assessed by optical coherence tomography at 6 months were compared between BRS- and EES-treated patients stratified according to post-dilatation status.

RESULTS

Primary percutaneous coronary intervention with post-dilatation was performed in 48 (50.5%) BRS- and 25 (25.5%) EES-treated lesions. There were no differences in baseline characteristics and post-procedural minimal lumen diameter between groups. In the BRS group, lesions with post-dilatation were associated with a trend toward a smaller minimal lumen area at 6 months (5.07 ± 1.68 mm² vs. 5.72 ± 1.77 mm²; p = 0.09) and significantly larger angiographic late lumen loss (0.28 ± 0.34 mm vs. 0.12 ± 0.25 mm; p = 0.02), whereas no difference was observed in the EES arm (5.46 ± 2.18 mm² vs. 5.55 ± 1.77 mm²; p = 0.85). The neointimal healing score was low and comparable between groups with and without post-dilation (BRS: 1.55 ± 2.61 vs. 1.92 ± 2.17; p = 0.48; EES: 2.50 ± 3.33 vs. 2.90 ± 4.80; p = 0.72).

CONCLUSIONS

In the setting of selected patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention with BRS or EES, post-dilatation did not translate into larger lumen area or improved arterial healing at follow-up. (ABSORB STEMI: The TROFI II; NCT01986803).

Late thrombotic events after bioresorbable scaffold implantation: a systematic review and meta-analysis of randomized clinical trials

Aims

To compare the long-term safety and efficacy of bioresorbable vascular scaffold (BVS) with everolimus-eluting stent (EES) after percutaneous coronary interventions.

Methods and results

A systematic review and meta-analysis of randomized clinical trials comparing clinical outcomes of patients treated with BVS and EES with at least 24 months follow-up was performed. Adjusted random-effect model by the Knapp-Hartung method was used to compute odds ratios (OR) and 95% confidence intervals (CI). The primary safety outcome of interest was the risk of definite/probable device thrombosis (DT). The primary efficacy outcome of interest was the risk of target lesion failure (TLF). Five randomized clinical trials (n = 1730) were included. Patients treated with Absorb BVS had a higher risk of definite/probable DT compared with patients treated with EES (OR 2.93, 95%CI 1.37-6.26, P = 0.01). Very late DT (VLDT) occurred in 13 patients [12/996 (1.4%, 95%CI: 0.08-2.5) Absorb BVS vs. 1/701 (0.5%, 95%CI: 0.2-1.6) EES; OR 3.04; 95%CI 1.2-7.68, P = 0.03], 92% of the VLDT in the BVS group occurred in the absence of dual antiplatelet therapy (DAPT). Patients treated with Absorb BVS had a trend towards higher risk of TLF (OR 1.48, 95%CI 0.90-2.42, P = 0.09), driven by a higher risk of target vessel myocardial infarction and ischaemia-driven target lesion revascularization. No difference was found in the risk of cardiac death.

Conclusion

Compared with EES, the use of Absorb BVS was associated with a higher rate of DT and a trend towards higher risk of TLF. VLDT occurred in 1.4% of the patients, the majority of these events occurred in the absence of DAPT.

Bioresorbable Coronary Scaffolds: Deployment Tips and Tricks and the Future of the Technology

Bioresorbable scaffolds (BRS) were developed as an alternative to drug-eluting stents (DES) to facilitate vessel restoration and reduce the risk of future adverse events. However, recent meta-analyses and "real-world" registries have raised some concern about the safety of this novel technology, especially due to an increased risk of thrombosis within the first weeks of scaffold implantation. These devices appear to be less forgiving to poor implantation strategies when compared to contemporary DES. Moreover, problems with the first generation of these devices-bulky struts and high crossing prolife, prolonged resorption time, lack of x-ray visibility, and limited tolerance to postdilation-have restricted their clinical application and negatively impacted their short- to mid-term safety performance. However, the potential for long-term improvements has encouraged further research into strategies to overcome these limitations, and potentially safer next-generation devices are already undergoing in-human clinical evaluations. Based on the current literature and our center's experience with these devices, this review discusses various approaches to optimize BRS implantation, drawbacks related to current-generation BRS, and potentially advantageous features of three next-generation scaffold systems.

Vascular response and healing profile of everolimus-eluting bioresorbable vascular scaffolds for percutaneous treatment of chronic total coronary occlusions: A one-year optical coherence tomography analysis from the GHOST-CTO registry

BACKGROUND

Bioresorbable vascular scaffolds (BVS) have been heralded with potential benefits that are especially desired in long lesions, including chronic total occlusions (CTOs). Procedural feasibility and mid-term outcomes of BVS in CTOs have been reported. However, there is still a paucity of data regarding the vascular and healing response to BVS in CTOs evaluated by optical coherence tomography (OCT).

METHODS

This study included prospectively 21 patients who had a CTO lesion treated with a BVS. Angiography and OCT scan were recorded at either post-implantation and 1-year follow-up. Quantitative coronary angiography and OCT analyses were performed by an independent core laboratory.

RESULTS

The angiographic analysis showed a significant increase in the percentage of in-segment diameter stenosis at 1year (11.89±9.5% vs. 21.84±11.7%; p=0.002). The OCT analysis showed a trend (p=0.07) towards increased mean scaffold area and significant reductions in mean lumen diameter (3.1±0.36mm vs. 2.85±0.47mm; p=0.0046), mean lumen area (7.8±1.73mm² vs. 6.76±2mm²; p=0.0082) and minimal lumen area (5.26±1.86mm² vs. 3.56±1.52mm²; p<0.0001). Malapposition area and volume decreased from 0.26±0.17mm² to 0.08±0.1mm² (p=0.0003) and from 14.17±12.92mm³ to 3.99±4.46mm³ (p=0.0014), respectively. The rate of uncovered or malapposed struts, measured at the frame level, was 5.29±6.48% at 1year.

CONCLUSIONS

In a small series of CTO patients treated with BVS implantation, OCT outcomes at 1year displayed an overall favorable vascular response and healing profile.

Possible mechanical causes of scaffold thrombosis: insights from case reports with intracoronary imaging

The advent of intracoronary stents has greatly increased the safety and applicability of percutaneous coronary interventions. One of the drawbacks of drug-eluting stents (DES) is the increased risk of late and very late stent thrombosis (ST). It was anticipated that the risks of ST after DES implantation would be solved with the advent of fully biodegradable scaffolds, which offer the possibility of transient scaffolding of the vessel to prevent acute vessel closure and recoil while also transiently eluting an antiproliferative drug to counteract constrictive remodelling and excessive neointimal hyperplasia. In spite of the enthusiasm for the concept of bioresorbable scaffolds, current clinical data on the Absorb bioresorbable vascular scaffold (BVS) have generated concerns about scaffold thrombosis (ScT) in both the early and late phases. However, the causes of ScT in both the early and late phases have yet to be fully elucidated. This article seeks to provide insights into the possible mechanical causes of ScT in the early and late phases with data stemming from intracoronary imaging (intravascular ultrasound and optical coherence tomography) of the currently published ScT cases following the implantation of BVS and reviews the practical recommendations for implantation of the BVS made by a group of experts.