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

First randomised controlled trial comparing the sirolimus-eluting bioadaptor with the zotarolimus-eluting drug-eluting stent in patients with de novo coronary artery lesions: 12-month clinical and imaging data from the multi-centre, international, BIODAPTOR-RCT

Background

The DynamX™ bioadaptor is the first coronary implant technology with a unique mechanism of unlocking the bioadaptor frame after polymer resorption over 6 months, uncaging the vessel while maintaining a dynamic support to the vessel. It aims to achieve the acute performance of drug-eluting stents (DES) with the advantages of restoration of vessel function.

Methods

This international, single blinded, randomised controlled (1:1) trial compared a sirolimus-eluting bioadaptor with a contemporary zotarolimus-eluting stent (DES) in 34 hospitals in Europe, Japan and New Zealand. Patients with de novo coronary lesions and absence of acute myocardial infarction were enrolled from January 2021 to Feburary 2022. The implantation of the bioadaptor followed the standards of DES. An imaging subset of 100 patients had angiographic and intravascular ultrasound assessments, and 20 patients additionally optical coherence tomography. Data collection will continue through 5 years, we herein report 12-month data based on an intention-to-treat population. This trial is registered at ClinicalTrials.gov (NCT04192747).

Findings

445 patients were randomised between January 2021 and February 2022. Device, lesion and procedural success rates, and acute gain were similar amongst the groups. The primary endpoint, 12-month target lesion failure, was 1.8% [95% CI: 0.5; 4.6] (n = 4) versus 2.8% [95% CI: 1.0; 6.0] (n = 6), pnon-inferiority < 0.001 for the bioadaptor and the DES, respectively (Δ-1.0% [95% CI: -3.3; 1.4]). One definite or probable device thrombosis occurred in each group. The 12-month imaging endpoints showed superior effectiveness of the bioadaptor such as in-device late lumen loss (0.09 mm [SD 0.34] versus 0.25 mm [SD 0.39], p = 0.04), and restored compliance and cyclic pulsatility (%mid in-device lumen area change of 7.5% versus 2.7%, p < 0.001).

Interpretation

This is the first randomised controlled trial comparing the novel bioadaptor technology against a contemporary DES. The bioadaptor demonstrated similar acute performance and 12-month clinical outcomes, and superior imaging endpoints including restoration of vessel function.

Funding

The study was funded by Elixir Medical.

Angiography-Based Superficial Wall Strain of De Novo Stenotic Coronary Arteries: Serial Assessment of Vessels Treated with Bioresorbable Scaffold or Drug-Eluting Stent

OBJECTIVES

This study sought to present an angiography-based computational model for serial assessment of superficial wall strain (SWS, dimensionless) of de-novo coronary stenoses treated with either bioresorbable scaffold (BRS) or drug-eluting stent (DES).

BACKGROUND

A novel method for SWS allows the assessment of the mechanical status of arteries in-vivo, which may help for predicting cardiovascular outcomes.

METHODS

Patients with arterial stenosis treated with BRS (n = 21) or DES (n = 21) were included from ABSORB Cohort B1 and AIDA trials. The SWS analyses were performed along with quantitative coronary angiography (QCA) at pre-PCI, post-PCI, and 5-year follow-up. Measurements of QCA and SWS parameters were quantified at the treated segment and adjacent 5-mm proximal and distal edges.

RESULTS

Before PCI, the peak SWS on the 'to be treated' segment (0.79 ± 0.36) was significantly higher than at both virtual edges (0.44 ± 0.14 and 0.45 ± 0.21; both p < 0.001). The peak SWS in the treated segment significantly decreased by 0.44 ± 0.13 (p < 0.001). The surface area of high SWS decreased from 69.97mm2 to 40.08mm2 (p = 0.002). The peak SWS in BRS group decreased to a similar extent (p = 0.775) from 0.81 ± 0.36 to 0.41 ± 0.14 (p < 0.001), compared with DES group from 0.77 ± 0.39 to 0.47 ± 0.13 (p = 0.001). Relocation of high SWS to device edges was often observed in both groups after PCI (35 of 82 cases, 41.7 %). At follow-up of BRS, the peak SWS remained unchanged compared to post-PCI (0.40 ± 0.12 versus 0.36 ± 0.09, p = 0.319).

CONCLUSION

Angiography-based SWS provided valuable information about the mechanical status of coronary arteries. Device implantation led to a significant decrease of SWS to a similar extent with either polymer-based scaffolds or permanent metallic stents.

24-Month Clinical Follow-Up and Mechanistic Insights From Intravascular Imaging Following Coronary Implantation of the Novel DynamX Bioadaptor Platform

BACKGROUND/PURPOSE

Conventional stents "cage" the coronary arteries, impairing vascular function and physiology. The DynamX Bioadaptor is a cobalt‑chromium platform with uncaging elements, designed to improve arterial pulsatility, vasomotion, compliance, and positive adaptive remodelling which may attenuate late clinical events associated with the caging of arteries through conventional stents. We present the first 24-month outcomes of this device.

METHODS/MATERIALS

This European multicenter study enrolled 50 patients with 50 de novo lesions treated with the DynamX Bioadaptor. Clinical follow-up is scheduled until 36 months and imaging follow-up was performed at 9-12 months.

RESULTS

24-month endpoints were target lesion failure (2 cardiac deaths), myocardial infarction (1 non-target vessel myocardial infarction), target vessel revascularisation (n = 0), and definite or probable device thrombosis (n = 0). No endpoint events occurred beyond 9 months. Paired intravascular ultrasound analysis of 18 patients from a single center revealed a 0.22 mm² increase in device cross-sectional area at 9-12 months. Pulsatility analysis showed an increase of in-device lumen area change by 46 % compared to the caged post-procedural configuration, reducing the compliance mismatch between the treated and not-treated vessel segments (segmental compliance). Likewise, vasomotion in response to nitroglycerin improved from 0.03mm² post-procedure to 0.17mm² at follow-up.

CONCLUSIONS

24-month clinical data demonstrate promising safety and efficacy of the DynamX Bioadaptor. Imaging data confirmed its unique capacity to improve arterial pulsatility, vasomotion, compliance and positive adaptive remodelling after "uncaging" which might have led to the promising clinical outcomes that need to be confirmed in larger studies.

Advances in the development of biodegradable coronary stents: A translational perspective

Implantation of cardiovascular stents is an important therapeutic method to treat coronary artery diseases. Bare-metal and drug-eluting stents show promising clinical outcomes, however, their permanent presence may create complications. In recent years, numerous preclinical and clinical trials have evaluated the properties of bioresorbable stents, including polymer and magnesium-based stents. Three-dimensional (3D) printed-shape-memory polymeric materials enable the self-deployment of stents and provide a novel approach for individualized treatment. Novel bioresorbable metallic stents such as iron- and zinc-based stents have also been investigated and refined. However, the development of novel bioresorbable stents accompanied by clinical translation remains time-consuming and challenging. This review comprehensively summarizes the development of bioresorbable stents based on their preclinical/clinical trials and highlights translational research as well as novel technologies for stents (e.g., bioresorbable electronic stents integrated with biosensors). These findings are expected to inspire the design of novel stents and optimization approaches to improve the efficacy of treatments for cardiovascular diseases.

•

Bioresorbable stents can overcome the limitations of non-degradable stents.

•

3D printing of shape-memory polymeric stents can lead to better clinical outcomes.

•

Advances in Mg-, Fe- and Zn-based stents from a translational perspective.

•

Electronic stents integrated with biosensors can covey stent status in real time.

•

Development in the assessment of stent performance in vivo.

Adaptive coronary artery rotational motion through uncaging of a drug-eluting bioadaptor aiming to reduce stress on the coronary artery

BACKGROUND

Caged drug-eluting stents impede natural coronary rotational motion and increase vessel stress, which can contribute towards adverse events. The DynamX™ Drug-Eluting Bioadaptor is a cobalt‑chromium platform with a novel mechanism that uncages the vessel after the bioresorbable coating resorbs over six months. This study aimed to analyze the effects of the rotational uncaging in a finite element analysis (FEA) model, validating its effect on coronary artery rotational motion through in-vivo stationary intravascular ultrasound (IVUS).

METHODS

Maximum Von Mises stresses were measured in an FEA model and compared for caged and uncaged bioadaptors. Stationary IVUS images from 20 patients enrolled in a single center were acquired post implantation and at 9-12-month follow-up to evaluate coronary artery rotational motion.

RESULTS

The FEA model showed that rotational uncaging of the bioadaptor reduces peak stress by 70%. In-vivo, the in-bioadaptor segment was significantly distorted post-implant compared to the native distal and proximal vessel, measured by IVUS: The sum of clockwise and counterclockwise rotational motion (net-effect rotational motion) was -2.7 ± 4.3° versus 0.5 ± 5.0° (proximal vessel), p = 0.036, and versus 0.2 ± 3.8° (distal vessel), p = 0.042. At follow up, when the bioadaptor had uncaged, the vessel returned towards its equilibrium (net-effect rotational motion -0.2 ± 5.6°), with no significant difference between the vessel segments.

CONCLUSIONS

In concurrence with the FEA observation, the in-vivo IVUS-analysis demonstrates that uncaging of the bioadaptor affects coronary artery rotational motion. The effect of these findings on reducing clinical events warrants further investigation.

Successful bailout stenting strategy against rare spontaneous retrograde dissection of partially absorbed magnesium-based resorbable scaffold: A case report

BACKGROUND

In the development of coronary stent technology, bioresorbable scaffolds are promising milestones in improving the clinical treatment of coronary artery disease. The “leave nothing behind” motto is the premise of the fourth revolution in percutaneous coronary intervention (PCI). Studies proving the safety and efficacy of the magnesium-based resorbable scaffolds (MgBRSs) include the BIOSOLVE-I and BIOSOLVE-II trials and the latest BIOSOLVE-IV registry. However, spontaneous retrograde dissection of a partially absorbed MgBRS may still occur, albeit rarely.

CASE SUMMARY

We describe an unusual case of coronary artery disease in a patient who had undergone a successful PCI 8 mo earlier, where an MgBRS was implanted into the left anterior descending artery (LAD) and left circumflex artery with drug-coated balloons for a ramus intermedius branch stenosis to achieve the “leave nothing behind” therapeutic intention and was currently presenting with a gradual worsening of chest tightness. The distal edge vascular response, during subsequent attempts with balloon angioplasty was performed smoothly. However, spontaneous retrograde dissection of a partially absorbed MgBRS in the LAD ensued. Successful bailout stenting was performed with revascularization of the entry and exit sites created by spontaneous dissection and complete sealing of the intramural hematoma. The patient recovered well and was discharged after 2 d of intervention. When followed up in August 2020 (7 mo later), the patient showed uneventful recovery.

CONCLUSION

Spontaneous retrograde dissection of a partially absorbed MgBRS was successfully treated using bailout sirolimus-eluting coronary stent strategy.

Early strut protrusion and late neointima thickness in the Absorb bioresorbable scaffold: a serial wall shear stress analysis up to five years

AIMS

The aim of the study was to evaluate the effect of strut protrusion (SP) on wall shear stress (WSS) and neointimal growth (NG) one and five years after implantation of an Absorb bioresorbable vascular scaffold.

METHODS AND RESULTS

Eight patients were selected from a first-in-man study. Following three-dimensional (3D) reconstruction of coronaries, WSS was quantified using Newtonian steady-flow simulation in each cross-section at 5° subunits (sectors) of the circumferential luminal surface. At one year, neointimal thickness (NT) was measured by optical coherence tomography (OCT) and correlated to WSS and SP post procedure. Median SP was 112.9 (90.8, 133.1) µm post implantation. Post procedure, a logarithmic inverse relationship between SP and post-implantation WSS (r=-0.425, p<0.001; correlation coefficients in a range from -0.143 to -0.553) was observed, whereas a correlation between baseline logarithm-transformed WSS (log-WSS) and NT (r=-0.451, p<0.001; correlation coefficients ranged from -0.140 to -0.662) was documented at one year. Mixed-effects analysis between baseline log-WSS and NT at follow-up yielded a slope of 30 µm/ln Pascal (Pa) and a y-intercept of 98 µm. As a result of NG, median flow area decreased from 6.91 (6.53, 7.48) mm2 post implantation to 5.65 (5.47, 6.02) mm2 at one-year follow-up (p=0.01) and to 5.75±1.37 mm2 at five-year follow-up (p=0.024). However, the vessel surface exposed to low WSS (<1 Pa) decreased significantly post procedure (42%) to one year (35.9%) and five years (15.2%) (p-overall <0.0001).

CONCLUSIONS

SP disturbs laminar flow, creates regions of low WSS (<1.0 Pa) that are associated with NG and lumen area reduction. Low WSS post implantation reduced significantly at long-term follow-up. Thin struts with effective embedment would substantially reduce NG and accelerate homogenisation of WSS towards physiological values.

Coronary Shear Stress after Implantation of Bioresorbable Scaffolds – a Modern Interdisciplinary Concept at the Border between Interventional Cardiology and Cardiac Imaging

Bioresorbable scaffolds/stents offer new and exciting perspectives in the treatment of patients with acute coronary syndromes, especially after the recent development of invasive imaging techniques, such as optical coherence tomography, which allow complete assessment of vascu-lar segments. A particular advantage of bioresorbable scaffolds is that once the biosorption of the scaffold is complete, the vascular segment regains its normal physiological functions, thus eliminating the risk of late complications. New studies show the importance of shear stress in the progression of vascular atherosclerosis or in accelerating endothelial turnover. Based on the current knowledge in this field, a future standardized determination of shear stress may help in the long-term follow-up of patients that have suffered or are at risk of developing an acute coronary syndrome.

Arterial Remodeling After Bioresorbable Scaffolds and Metallic Stents

BACKGROUND

Although previous observational studies have documented late luminal enlargement and expansive remodeling following implantation of a bioresorbable vascular scaffold (BVS), no comparison with metallic stents has been conducted in a randomized fashion.

OBJECTIVES

This study sought to compare vessel remodeling patterns after either Absorb BVS or Xience metallic drug-eluting stent (DES) implantation (Abbott Vascular, Santa Clara, California) and determine the independent predictors of remodeling.

METHODS

In the ABSORB II randomized trial, 383 lesions (n = 359) were investigated by intravenous ultrasound both post-procedure and at 3-year follow-up. According to vessel and lumen area changes over 3 years, we categorized 9 patterns of vessel remodeling that were beyond the reproducibility of lumen and vessel area measurements.

RESULTS

The relative change in mean vessel area was significantly greater with the BVS compared to the DES (6.7 ± 12.6% vs. 2.9 ± 11.5%; p = 0.003); the relative change in mean lumen area was significantly different between the 2 arms (1.4 ± 19.1% vs. -1.9 ± 10.5%, respectively; p = 0.031). Multivariate analysis indicated that use of the BVS, female sex, balloon-artery ratio >1.25, expansion index ≥0.8, previous percutaneous coronary intervention, and higher level of low-density lipoprotein cholesterol were independent predictors of expansive remodeling. Furthermore, in the BVS arm, necrotic core pre-procedure was an independent determinant of expansive remodeling.

CONCLUSIONS

Expansive vessel wall remodeling was more frequent and intense with the BVS than the metallic DES and could be determined by patient baseline characteristics and periprocedural factors. The clinical effect of the observed lumen and vessel remodeling must be investigated in further large clinical studies to optimize the clinical outcome of patients and lesions treated by bioresorbable scaffolds. (ABSORB II Randomized Controlled Trial; NCT01425281).

First-in-Man Trial of SiO2 Inert-Coated Bare Metal Stent System in Native Coronary Stenosis - The AXETIS FIM Trial

BACKGROUND

A novel bare metal stent with an SiO₂coating was developed to prevent excessive neointimal hyperplasia by inertization of the metallic stent surface. The efficacy of the device was demonstrated in a preclinical model. The aim of this first-in-man trial was to assess the safety and feasibility of the new device.Methods and Results:This prospective non-randomized single-arm trial was designed to enroll 35 patients with a de novo coronary lesion. Quantitative coronary angiography and optical coherence tomography (OCT) were performed at the baseline procedure and at the 6-month follow-up. Stent implantation was performed with OCT guidance according to optimal stent implantation criteria. The trial was terminated upon the advice of the data safety monitoring board after enrolling 14 patients due to the high incidence of re-intervention. Optimal OCT implantation criteria were achieved in only 8.3% of lesions. At 6 months, angiographic in-stent late lumen loss as the primary endpoint was 0.77±0.44 mm, and binary restenosis occurred in 33.3% of lesions. At the 6-month OCT, neointimal volume obstruction was 32.8±15.6% with a neointimal thickness of 237±117 µm. At 12 months, the device-oriented composite endpoint (defined as cardiac death, target vessel myocardial infarction, and clinically indicated target lesion revascularization rate) was 33.3%.

CONCLUSIONS

In contrast with the preclinical study, the Axetis stent did not efficiently suppress neointimal hyperplasia in humans in this trial.

Impact of Implantation Technique and Plaque Morphology on Strut Embedment and Scaffold Expansion of Polylactide Bioresorbable Scaffold - Insights From ABSORB Japan Trial

BACKGROUND

The optimal implantation technique for the bioresorbable scaffold (Absorb, Abbott Vascular) is still a matter of debate. The purpose of the present study was to evaluate the effect of implantation technique on strut embedment and scaffold expansion.Methods and Results:Strut embedment depth and scaffold expansion index assessed by optical coherence tomography (OCT) (minimum scaffold area/reference vessel area) were evaluated in the ABSORB Japan trial (OCT subgroup: 87 lesions) with respect to implantation technique using either quantitative coronary angiography (QCA) or OCT. Strut embedment was assessed at the strut level (n=667), while scaffold expansion was assessed at the lesion level (n=81). The mean embedment depth was 63±59 µm. Balloon sizing and inflation pressure had no direct effect on strut embedment. Plaque morphology affected strut embedment [nonatherosclerotic (58.9±54.3 µm), fibroatheroma (73.3±59.6 µm), fibrous plaque (59.7±51.1 µm), and fibrocalcific plaque (-3.1±61.6 µm, negative value means malapposition), P <0.001]. The balloon-artery ratio positively correlated with the expansion index. This relationship was stronger when the OCT-derived reference vessel diameter (RVD) was used as a reference for balloon selection rather than the QCA-derived one [predilatation (Pearson correlation r: QCA: 0.167 vs. OCT: 0.552), postdilatation (QCA: 0.316 vs. OCT: 0.717)].

CONCLUSIONS

Underlying plaque morphology influenced strut embedment, whereas implantation technique had no direct effect on it. Optimal balloon sizing based on OCT-derived RVD might be recommended. However, the safety of such a strategy should be investigated in a prospective trial. (Circ J 2016; 80: 2317-2326).

Bioresorbable vascular scaffolds - basic concepts and clinical outcome

The introduction of percutaneous treatment of coronary artery stenosis with balloon angioplasty was the first revolution in interventional cardiology; the advent of metallic coronary stents (bare and drug-eluting) marked the second and third revolutions. However, the latest generation of drug-eluting stents is limited by several factors. Permanent vessel caging impairs arterial physiology, and the incidence of very late stent thrombosis - although lower with the second generation than with the first generation of drug-eluting stents - remains a major concern. This complication is mainly related to the presence of permanent metallic implants, chronic degeneration triggered by an inflammatory response to the coating polymer, and/or adverse effects of antiproliferative drugs on endothelial regeneration. In 2011, self-degrading coronary stents - the bioresorbable vascular scaffolds (BVS) - were introduced into clinical practice, showing good short-term results owing to their adequate strength. The advantage of these devices is the transient nature of vascular scaffolding, which avoids permanent vessel caging. In this Review, we summarize the latest research on BVS, with a particular emphasis on the implantation technique (which is different from that used with metallic stents) to outline the concept that BVS deployment methods have a major effect on procedural success and prognosis of patients with coronary artery stenosis. Furthermore, the clinical outcome of BVS in randomized clinical trials and in phase IV studies are discussed in different pathophysiological settings, such as stable or acute coronary disease. Finally, all the available data on the safety profile of BVS regarding scaffold thrombosis are discussed.