Ten-year clinical outcomes of everolimus- and biolimus-eluting coronary stents vs. everolimus-eluting bioresorbable vascular scaffolds-insights from the EVERBIO-2 trial

Background

Bioresorbable vascular scaffolds (BVSs) have been developed as a potential solution to mitigate late complications associated with drug-eluting metallic stents (DESs) in percutaneous coronary intervention for coronary artery disease. While numerous studies have compared BVSs to DESs, none have assessed clinical outcomes beyond 5 years.

Objectives

This study aimed to compare the 10-year clinical outcomes of patients treated with BVSs vs. DESs.

Methods

The EverBio-2 trial (Comparison of Everolimus- and Biolimus-Eluting Coronary Stents with Everolimus-Eluting Bioresorbable Vascular Scaffold) is a single-center, assessor-blinded, randomized controlled trial that enrolled 240 patients allocated in a 1:1:1 ratio to receive BVSs, everolimus-eluting stents, or biolimus-eluting stents (BESs). Clinical follow-up was scheduled for 10 years.

Results

Clinical follow-up was completed in 222 patients (93%) at the 10-year mark. The rate of device-oriented composite events (DOCE) was 28% in the DES group and 29% in the BVS group (p = 0.72) at 10 years. Similarly, the rate of patient-oriented composite events (POCE) was 55% in the DES group and 49% in the BVS group (p = 0.43) at 10 years. Notably, the rate of myocardial infarction (MI) within the target vessel was 5% in the BVS group and 0% in the BES group (p = 0.04), while the rate of any MI was 10% in the BVS group and 2% in the BES group (p = 0.04). In addition, the rate of Academic Research Consortium (ARC) possible stent thrombosis was 3% in the BVS group and 0% in the DES group (p = 0.04).

Conclusions

Over 10 years, the rates of clinical DOCE and POCE were similar between the BVS and DES groups but individual outcomes of stent thrombosis were higher (3%) in the BVS group compared to the DES group.

Clinical Trial Registration

ClinicalTrials.gov, identifier (NCT01711931).

Fully bioresorbable vascular scaffolds: lessons learned and future directions

Fully bioresorbable scaffolds (BRS) were designed to overcome the limitations of metallic drug-eluting stents, which permanently cage the vessel wall, thereby preventing normal coronary vasomotion, preclude bypass grafting and can provoke long-term foreign-body responses. Although multiple scaffolds have been or are in development, the Absorb Bioresorbable Vascular Scaffold (BVS; Abbott Vascular) was the first FDA-approved device and was widely expected to fulfil the dream of interventional cardiologists of a transient scaffold that would disappear 'when the job was done' and would not hamper further treatment options. Although early, small studies and even large, randomized trials showed beneficial outcomes up to 1 year of follow-up, longer-term results have been disappointing, with increased rates of device thrombosis and target-lesion revascularization. The Absorb BVS device was withdrawn from the market because of low demand. In this Review, we summarize the preclinical and clinical data available for BRS to understand how the vascular biological reactions to these devices differ from biological reactions to metallic drug-eluting stents and how these responses translate into clinical outcomes. We also discuss next-generation BRS and outline modifications that are needed to improve the long-term outcomes with these devices so that they eventually become a viable option for patients with symptomatic obstructive coronary artery disease.

The 1‑year safety and efficacy outcomes of Absorb bioresorbable vascular scaffolds for coronary artery disease treatment in diabetes mellitus patients: the ABSORB DM Benelux study

BACKGROUND

Diabetes mellitus (DM) patients show higher rates of repeat revascularisation even in the era of modern drug-eluting stents (DES). The concept of bioresorbable scaffolds is becoming captivating, as it might allow for repeat interventions, prolonging the time span during which patients can be treated by percutaneous coronary intervention (PCI).

AIMS

We intend to evaluate the short- and long-term safety and efficacy of Absorb bioresorbable vascular scaffolds (Absorb BVS) in the treatment of coronary artery disease (CAD) in DM patients for any indication.

METHODS

The ABSORB DM Benelux is an international prospective study in DM patients who have undergone PCI with ≥1 Absorb BVS. Major adverse cardiac events (MACE) at 1 year was the primary endpoint, defined as a composite of all-cause death, any myocardial infarction (MI) and ischaemia-driven target vessel revascularisation (TVR). Secondary endpoints were target lesion failure (TLF) and definite or probable scaffold thrombosis (ScT).

RESULTS

Between April 2015 and March 2017, 150 DM patients and 188 non-complex lesions were treated. Device implantation was successful in 100%. MACE occurred in 14 (9.5%) patients, with all-cause death occurring in 4 (2.7%), any MI in 6 (4.1%) and ischaemia-driven TVR in 7 (4.8%) respectively. TLF was reported in 11 (7.5%). Definite and probable ScT was observed in 2 (1.4%).

CONCLUSION

Absorb BVS for treatment of anatomically low-risk patients with DM show acceptable safety and efficacy outcomes at 1 year. If these promising results are confirmed after a longer follow-up period, new-generation bioresorbable scaffolds combined with refinement of implantation techniques might open new horizons for CAD treatment in DM patients.

Development of a radiopaque, long-term drug eluting bioresorbable stent for the femoral-iliac artery

Tubular tissues exist in various forms purported for blood supply, waste secretion, etc. to aid proper function and maintenance of the human body. Under pathological conditions, however, these tissues may undergo stenosis. A major surgical treatment for stenosis is to implant a medical device called a stent which aims to expand the narrowed tissue and maintain its patency. Most stents are currently made from metals; despite their high mechanical strength, however, interactions with the host tissue often results in restenosis and stent fracture. To solve these problems, a bioresorbable stent (BRS) is proposed as a next generation stent. In this study, a rotating rod combined 3D printing system was developed to fabricate various types of BRSs. In addition, we confirmed that a 1.5 year long-term release of paclitaxel is possible using polymeric materials. Moreover, a stent loaded with contrast powder was fabricated and was successfully viewed under fluoroscopy. The stent was then implanted in the iliac arteries of pigs and no adverse events were observed for up to 8 weeks.

Multimodality intravascular imaging of bioresorbable vascular scaffolds implanted in vein grafts

INTRODUCTION

There are no data presenting a serial assessment of vein graft healing after bioresorbable vascular scaffold (BVS) implantation at long-term follow-up.

AIM

To describe ABSORB BVS healing in vein grafts by optical coherence tomography (OCT) and high-definition intravascular imaging (HD-IVUS) at long-term follow-up.Material and methods: The study group consisted of 6 patients. The first patient had serial OCT assessment of BVS implanted in the saphenous vein grafts (SVG) at baseline and at 3-, 6-, 18-month follow-up and the second patient had OCT assessment of BVS implanted in the SVG at baseline and 24-, 48-month follow-up. The second and the third patients had OCT and HD-IVUS imaging at baseline and 48-month follow-up. The last 3 patients had OCT imaging of BVS implanted in the native coronary artery at 48-month follow-up.

RESULTS

There were no differences in neointimal hyperplasia after BVS implantation between each time point. However, complete scaffold coverage was observed only 48 months after implantation. Out of 202 analyzed scaffold struts, there were 67 (33%) black boxes detectable at 48-month follow-up. HD-IVUS presented plaque burden up to 67% at the segment of BVS implantation at 48-months follow-up. There was a difference in neointimal hyperplasia thickness (1.27 (0.953-1.696) vs. 0.757 (0.633-0.848), p < 0.001) between a native coronary artery and BVS scaffolds at 48-month follow-up.

CONCLUSIONS

Bioresorbable vascular scaffold implanted in SVG characterized moderate neointimal hyperplasia as excessive as compared to native coronary arteries at long-term follow-up. The complete scaffold coverage was observed only 48 months after implantation.

Mechanical properties and degradation of drug eluted bioresorbable vascular scaffolds prepared by three-dimensional printing technology

Bioresorbable vascular scaffolds are expected to replace the traditional metal stent, avoiding the long-term complications of metal stents. However, it is hard for the traditional scaffold manufacturing process to meet the requirements of individualized treatment for vascular lesions, which requires different morphologies. Here, we used a new method of scaffold manufacturing, three-dimensional printing technology, to prepare bioresorbable vascular scaffolds. The fabricated scaffold was loaded with sirolimus mixed with scaffold preparation material for slow drug release. The engineered, drug- loaded, bioresorbable vascular scaffold (BVS) was analyzed and tested in vivo. The scaffolds produced by three-dimensional printing technology exhibited good mechanical properties and in vitro degradation performance. The results also suggested that these scaffolds could maintain effective radial strength after long-term degradation and sustained release of the drug. As a new scaffold preparation method, it may provide a promising idea for developing bioresorbable vascular scaffold technology.

Everolimus-eluting bioresorbable scaffolds for treatment of coronary artery disease in patients with diabetes mellitus: the midterm follow-up of the prospective ABSORB DM Benelux study

Background

Percutaneous coronary intervention (PCI) in patients with diabetes mellitus (DM) remains challenging even with modern drug-eluting stents (DES) due to high rates of repeat revascularization. Everolimus-eluting bioresorbable scaffolds (EE-BRS) might allow for repeat intervention prolonging the time interval of percutaneous treatment options.

Methods

The ABSORB DM Benelux Study is a dedicated prospective, international study to evaluate the midterm safety and efficacy of EE-BRS in DM patients. All DM patients that received ≥ 1 EE-BRS for any indication were enrolled and prospectively followed. Study endpoints were major adverse cardiac events (MACE): a composite of all-cause death, any myocardial infarction (MI) and ischemic-driven target vessel revascularization (TVR); target lesion failure (TLF): a composite of cardiac death (CD), target vessel MI, and ischemic-driven target lesion revascularization (TLR), as well as definite or probable scaffold thrombosis (ScT).

Results

Between April 2015 till March 2017, 150 DM patients and 188 lesions were treated and followed up to 3 years. Device implantation success was 100%. MACE occurred in 15.2% (event rate of 8.8 per 100 PY). TLF was reported in 11.7% (7.0 events per 100 PY). CD, target vessel MI, ischemic-driven TLR occurred in 3.4%, 3.6% and 5.5% respectively, while ScT was observed in 1.4%. There were no occurrences of late or very late ScT.

Conclusion

EE-BRS treatment in DM patients shows comparable midterm safety and efficacy outcomes when historically compared with modern DES. New-generation EE-BRS might offer an attractive alternative to metallic DES in treatment of fast progressing atherosclerosis population as in DM patients.

Trial registration NTR5447. Registered 05 October 2015, retrospectively registered

The Crimping and Expanding Performance of Self-Expanding Polymeric Bioresorbable Stents: Experimental and Computational Investigation

Abstract: Polymeric bioresorbable stents (PBRSs) are considered the most promising devices to treat cardiovascular diseases. However, the mechanical weakness still hampers their application. In general, PBRSs are crimped into small sheathes and re-expanded to support narrowed vessels during angioplasty. Accordingly, one of the most significant requirements of PBRSs is to maintain mechanical efficacy after implantation. Although a little research has focused on commercial balloon-expanding PBRSs, a near-total lack has appeared on self-expanding PBRSs and their deformation mechanisms. In this work, self-expanding, composite polymeric bioresorbable stents (cPBRSs) incorporating poly(p-dioxanone) (PPDO) and polycaprolactone (PCL) yarns were produced and evaluated for their in vitro crimping and expanding potential. Furthermore, the polymer time-reliable viscoelastic effects of the structural and mechanical behavior of the cPBRSs were analyzed using computational simulations. Our results showed that the crimping process inevitably decreased the mechanical resistance of the cPBRSs, but that this could be offset by balloon dilatation. Moreover, deformation mechanisms at the yarn level were discussed, and yarns bonded in the crossings showed more viscous behavior; this property might help cPBRSs to maintain their structural integrity during implantation.

The development of bioresorbable composite polymeric implants with high mechanical strength

Implants for the treatment of tissue defects should mimic the mechanical properties of the native tissue of interest and should be resorbable as well as biocompatible. In this work, we developed a scaffold from variants of poly(glycolic) acid which were braided and coated with an elastomer of poly(glycolide-co-caprolactone) and crosslinked. The coating of the scaffold with the elastomer led to higher mechanical strength in terms of compression, expansion and elasticity compared to braids without the elastomer coating. These composite scaffolds were found to have expansion properties similar to metallic stents, utilizing materials which are typically much weaker than metal. We optimized the mechanical properties of the implant by tuning the elastomer branching structure, crosslink density, and molecular weight. The scaffolds were shown to be highly resorbable following implantation in a porcine femoral artery. Biocompatibility was studied in vivo in an ovine model by implanting the scaffolds into femoral arteries. The scaffolds were able to support an expanded open lumen over 12 months in vivo and also fully resorbed by 18 months in the ovine model.

Conformability in everolimus-eluting bioresorbable scaffolds compared with metal platform coronary stents in long lesions

The aim of this study was to determine if there are significant differences in curvature of the treated vessel after the deployment of a polymeric BRS or MPS in long lesions. The impact of long polymeric bioresorbable scaffolds (BRS) compared with metallic platform stents (MPS) on vessel curvature is unknown. This retrospective study compares 32 patients who received a single everolimus-eluting BRS with 32 patients treated with a single MPS of 28 mm. Quantitative coronary angiography (QCA) was used to evaluate curvature of the treatment and peri-treatment region before and after percutaneous coronary intervention (PCI). Baseline demographic and angiographic characteristics were similar between the BRS and MPS groups. Pretreatment lesion length was 22.19 versus 20.38 mm in the BRS and MPS groups respectively (p = 0.803). After treatment, there was a decrease in median diastolic curvature in the MPS group (from 0.257 to 0.199 cm^-1, p = 0.001). A similar trend was observed in the BRS group but did not reach statistical significance (median diastolic curvature from 0.305 to 0.283 cm^-1, p = 0.056). Median Percentage relative change in diastolic curvature was lower in the BRS group compared with the MPS group (BRS vs. MPS: 7.48 vs. 29.4%, p = 0.013). By univariate analysis, use of MPS was an independent predictor of change in diastolic curvature (p = 0.022). In the deployment of long coronary scaffolds/stents (28 mm in length), BRS provides better conformability compared with MPS.

Everolimus-Eluting Bioresorbable Vascular Scaffold in Real World Practice - A Single Center Experience

BACKGROUND

Drug-eluting stents are widely used in coronary artery intervention. However, vessel caging and very late thrombotic events are of persistent and substantial concern. Bioresorbable vascular scaffolds (BVS) were developed to deliver vascular reparative therapy, by eliminating permanent mechanical restraint. However, data regarding its clinical performance is lacking.

METHODS

After the BVS implantation procedure received national approval in May 2014, patients receiving BVS implantation until November 2014 in National Taiwan University Hospital (NTUH) were enrolled. Clinical variables, angiographic data, procedural details, and follow-up information were collected and compared with those receiving BVS at NTUH as part of the global ABSORB EXTEND trial.

RESULTS

A total of 35 patients (38 target vessels) with 48 BVS implanted after approval were enrolled, as the "real-world practice" group. Data of the 34 patients (34 target vessels) with 37 BVS implanted in the ABSORB EXTEND trial were also obtained. Differences in lesion complexity (0% type B2/C lesion in ABSORB EXTEND, versus 23.7% in real-world, p = 0.007) and lesion length (20.9 ± 6.1 mm in ABSORB EXTEND, versus 29.5 ± 15.9 mm in real-world, p = 0.008) were noted. The ischemia-driven target vessel revascularization after an average of 732 days follow-up was 11.8% in the ABSORB EXTEND trial. However, there was no ischemia-driven target lesion revascularization (TLR), no scaffold thrombosis, no myocardial infarction (MI), and no patients passed during the follow-up period. In real-world patients, there is 5.3% of MI, 2.6% ischemia-driven TLR, and 2.6% of non-fatal probable scaffold thrombosis.

CONCLUSIONS

The use of BVS in real-world practice is feasible, with clinical outcomes comparable to those in the ABSORB EXTEND trial.

Restenosis After Everolimus-eluting Vascular Scaffolding. Angiographic and Optical Coherence Tomography Characterization

INTRODUCTION AND OBJECTIVES

Coronary restenosis after bioresorbable vascular scaffold (BVS) implantation is infrequent and little information is available on the main characteristics of these lesions. The aim of this study was to assess restenotic lesions by using optical coherence tomography (OCT).

METHODS

We studied 330 patients with coronary artery disease who received 398 BVS to treat 380 lesions. These patients were clinically and angiographically evaluated at follow-up and OCT was carried out on detection of restenosis.

RESULTS

After a follow-up of 19 ± 10 months, 18 restenotic lesions were detected in 17 patients (5.4%). Depending on the time of presentation, most cases of restenosis were late or very late (9 ± 4 months). The most frequent angiographic pattern was focal restenosis in 12 (67%) patients, which was mainly located at the proximal border in 9 (75%) whether involving the scaffold or not. The homogeneous pattern was infrequent, occurring in 3 (25%) lesions and was only visualized in 3 out of 6 cases of restenosis located at the margin. When the focal restenosis was located in the platform, OCT showed a heterogeneous or layered pattern. Finally, diffuse restenosis was observed in 6 patients (33%). In diffuse restenosis, OCT revealed a lipid-laden or layered tissue structure and the presence of microvessels or microcalcification, potentially suggesting a neoatherosclerotic process.

CONCLUSIONS

After a mean follow-up of 19 months, the restenosis rate was 5.4%. Most restenotic lesions were focal, located at the proximal border. Diffuse restenosis mostly occurred late or very late and most showed signs suggestive of neoatherosclerosis.

Bioabsorbable vascular scaffold overexpansion: insights from in vitro post-expansion experiments

AIMS

While bioresorbable vascular scaffolds (BVS) are increasingly used in clinical practice, their behaviour when post-dilated beyond their recommended maximum overexpansion diameter remains sparsely documented. We aimed to test the overexpansion of the BVS scaffold in vitro and evaluate the impact of excessive scaffold oversizing on focal point support.

METHODS AND RESULTS

We examined the post-expansion behaviour of the bioresorbable vascular scaffold (3.0 mm and 3.5 mm Absorb BVS; Abbott Vascular, Santa Clara, CA, USA) after overexpansion with non-compliant (NC) balloons of increasing diameters. After each oversizing step, the scaffolds were measured and inspected for strut disruption using microscope and optical coherence tomography imaging. Point force mechanical measurements on single scaffold struts were also performed to evaluate the impact of excessive scaffold overstretching on focal mechanical support. 3.0 mm and 3.5 mm scaffold sizes could be post-expanded up to 1 mm above their nominal diameters without any strut fracture when deployed without an external constraining model. Importantly, when overexpansion of both scaffold sizes was repeated using a constraining silicone lesion model, only post-expansion with an NC balloon size 0.5 mm larger than the scaffold nominal sizes could be performed without strut fractures. Point force compression analysis on single struts shows that overstretched struts with fractures provided lower focal strength compared to overexpanded ring segments without fractures and normal segments expanded at nominal pressure.

CONCLUSIONS

In our experiments, only overexpansion with an NC balloon 0.5 mm larger than the BVS size was feasible for BVS deployed inside an arterial lesion model. Overexpansion of the BVS scaffold beyond recommended post-dilation limits can lead to strut disconnections and focal loss of mechanical support.

A review of bioresorbable scaffolds: hype or hope?

In the field of percutaneous coronary intervention, the evolution of coronary metal stents has been well established for the past three decades, but research on bioresorbable scaffolds has only gained momentum in the recent past. Although second-generation drug-eluting metal stents are the gold standard for the treatment of obstructive coronary artery disease, a few drawbacks exist. The development of bioresorbable scaffolds is an attempt to overcome the limitations of metal stents. This review highlights the rationale for the bioresorbable scaffold, its properties and potential applications. It also focuses on the current evidence and concerns regarding the application of the bioresorbable scaffold in day-to-day practice.

Treatment of the femoropopliteal artery with the bioresorbable REMEDY stent

OBJECTIVE

Bioresorbable stents are an emerging technology in the endovascular treatment of femoropopliteal lesions. They address the issue of leaving permanent stents in the treated arterial segment that are only temporarily needed to treat dissection or recoil. The REMEDY stent (Kyoto Medical Planning Co, Kyoto, Japan) was the first commercially available biodegradable scaffold for peripheral use. We evaluated its performance and safety in the treatment of short femoropopliteal stenosis or occlusion.

METHODS

A prospective, multicenter, observational registry was set up of patients in Rutherford-Becker categories 2 to 5 with femoropopliteal lesions that could be treated with one REMEDY stent. Clinical examination and duplex ultrasound imaging were performed at 1, 6, and 12 months. The primary end point was absence of clinically driven target lesion revascularization at 12 months. Secondary end points were technical and clinical success, primary and secondary patency rate, clinically driven target vessel revascularization, major complications, and Rutherford-Becker classification at 6 and 12 months.

RESULTS

The registry enrolled 99 patients between January 2011 and July 2013 in 12 centers in Belgium. Most lesions were determined as TransAtlantic Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II) A (n = 80) and located in the superficial femoral artery (n = 91). There were 19 total occlusions (mean length, 41.3 mm) and 80 stenoses (mean length, 37.5 mm). Technical success was achieved in 96 patients, and clinical success was obtained in 95. Target lesion revascularization, which equalled target vessel revascularization, was 19% at 6 months and rose to 33% at 12 months. Primary patency was 68% at 6 months and 58% at 12 months. Secondary patency was 85% at 6 months and 86% at 12 months. After 12 months, two patients had undergone an amputation.

CONCLUSIONS

The 1-year follow-up results of the REMEDY stent do not meet current standards set by nitinol stents. Given the significant issues concerning bioresorbable stents in femoropopliteal arteries, their use outside clinical trials should be withheld until improvements are made and better data are available.

Optimisation of percutaneous coronary intervention: indispensables for bioresorbable scaffolds

INTRODUCTION

With new developments in percutaneous coronary intervention (PCI), such as the introduction of bioresorbable scaffolds (BRS), percutaneous treatment of coronary artery diseases has entered a new era. Without metallic remnants, BRSs appear able to overcome several limitations of the existing metallic stents and provide a physiologic treatment of coronary artery pathology.

AREAS COVERED

BRS have different mechanical properties compared to the traditional metallic stents that should be taken into account during their implantation. Lesion selection, device sizing and satisfied pre-dilatation should be implemented prudently. Although intravascular imaging is not mandatory for the implantation of BRSs it may have a value in optimizing device deployment assess final results and reduce the risk of device related adverse events such as re-stenosis, or scaffold thrombosis. This review aims to reveal the crucial points about the methods of optimization in each steps of BRS implantation. Expert commentary: The target lesions for BRS should be selected meticulously. Pre-dilatation, post-dilatation and intra-vascular imaging techniques should be implemented appropriately to avoid undesirable events after scaffold implantation.

"Assessment of effectiveness and security in high pressure postdilatation of bioresorbable vascular scaffolds during percutaneous coronary intervention. Study in a contemporary, non-selected cohort of Spanish patients"

OBJECTIVES

To determine security and benefits of high pressure postdilatation (HPP) of bioresorbable vascular scaffolds (BVS) in percutaneous coronary intervention (PCI) of complex lesions whatever its indication is.

BACKGROUND

Acute scaffold disruption has been proposed as the main limitation of BVS when they are overexpanded. However, clinical implications of this disarray are not yet clear and more evidence is needed.

METHODS

A total of 25 BVS were deployed during PCI of 14 complex lesions after mandatory predilatation. In all cases HPP was performed with NC balloon in a 1:1 relation to the artery. After that, optical coherence tomography (OCT) analyses were performed.

RESULTS

Mean and maximal postdilatation pressure were 17±3.80 and 20 atmospheres (atm) respectively. Postdilatation balloon/scaffold diameter ratio was 1.01. A total of 39,590 struts were analyzed. Mean, minimal and maximal scaffold diameter were respectively: 3.09±0.34mm, 2.88±0.31mm and 3.31±0.40mm. Mean eccentricity index was 0.13±0.05. ISA percentage was 1.42% with a total of 564 malapposed struts. 89 struts were identified as disrupted, which represents a percentage of disrupted struts of 0.22%. At 30days, none of our patients died, suffered from stroke, stent thrombosis or needed target lesion revascularization (TLR).

CONCLUSIONS

NC balloon HPP of BVS at more than 17atm (up to 20atm) is safe during PCI and allows to achieve better angiographic and clinical results.

Bioresorbable Vascular Scaffold for the Treatment of Coronary Bifurcation Lesions: Immediate Results and 1-year Follow-up

INTRODUCTION AND OBJECTIVES

The treatment of coronary lesions with a bioresorbable vascular scaffold has been shown to be effective. However there is little information about its use in bifurcations. The aim of this study was to analyze the safety and efficacy of the bioresorbable scaffold in the treatment of coronary bifurcation lesions.

METHODS

From January 2012 to January 2015, we used a bioresorbable vascular scaffold to treat 194 patients with 230 bifurcation lesions. The scaffold geometry was examined by intracoronary imaging techniques in 145 bifurcations (65%). In all, 78% of the bifurcations were evaluated angiographically during follow-up (computed tomography angiography in 138 and coronary angiography in 41).

RESULTS

The most common clinical presentation was acute coronary syndrome (81%). The most frequent type of bifurcation was 1,1,1 (34%). A simple approach was the chosen strategy in 221 bifurcations (96%). In 90 of these lesions, the side branch was postdilated through the cells of the platform and, in 3 cases, strut fractures were observed in optical coherence tomography. Procedural success was achieved in all patients. There was 1 case of subacute thrombosis and 1 sudden cardiac death during the first month. The duration of angiographic follow-up was 7.3±1.6 months and that of clinical follow-up, 14±6 months. Twelve (5%) restenoses were documented and revascularized. During follow-up, 2 patients (1%) had an infarction in another territory and another 2 patients (1%) died; the remaining patients had a symptom-free follow-up. The incidence of thrombosis was 1.3%.

CONCLUSIONS

Treatment of bifurcation coronary lesions using a provisional approach is feasible and safe, with a low rate of adverse events.

Patency of coronary side branches covered by an everolimus-eluting bioresorbable vascular scaffold: clinical outcomes and computed tomography scan follow-up

AIMS

The behaviour of side branches (SBs) covered by a bioresorbable vascular scaffold (BVS) is not well known. This study analysed the rate of side branch occlusion (SBO) immediately after BVS implantation, its clinical impact, predictors of SBO and the fate of such SBs at follow-up.

METHODS AND RESULTS

We assessed 140 patients with 346 jeopardised SBs divided into three groups: small (<1 mm, n=181), intermediate (1-2 mm, n=102) and large (>2 mm, n=63). SBO was defined as a TIMI flow 0 or 1. Computed tomography was scheduled at six months for patients with jailed SBs >1 mm. Immediate occlusion occurred in 31 (9%) SBs: 22 (12%) small, 8 (8%) intermediate and one (1.6%) large, while post-procedural SBO was 5.5%. In-hospital events included one thrombosis (0.7%) and eight non-Q-wave myocardial infarctions (6%). After 17±3 months, one patient died (0.7%) and six patients needed repeat revascularisation (4%). Re-evaluation showed no late SBO at 7±3 months. Predictors of SBO were: small SBs (OR 2.06, 95% CI: 1.08-4.63; p<0.05) and stenosis >50% at the origin (OR 17.22, 95% CI: 7.79-38.10; p<0.01).

CONCLUSIONS

The incidence of SBO and its clinical impact were low when SBs >1 mm were covered. These favourable results were maintained at midterm.

Bioresorbable scaffolds: a new paradigm in percutaneous coronary intervention

Numerous advances and innovative therapies have been introduced in interventional cardiology over the recent years, since the first introduction of balloon angioplasty, but bioresorbable scaffold is certainly one of the most exciting and attracting one. Despite the fact that the metallic drug-eluting stents have significantly diminished the re-stenosis ratio, they have considerable limitations including the hypersensitivity reaction to the polymer that can cause local inflammation, the risk of neo-atherosclerotic lesion formation which can lead to late stent failure as well as the fact that they may preclude surgical revascularization and distort vessel physiology. Bioresorbable scaffolds overcome these limitations as they have the ability to dissolve after providing temporary scaffolding which safeguards vessel patency. In this article we review the recent developments in the field and provide an overview of the devices and the evidence that support their efficacy in the treatment of CAD. Currently 3 devices are CE marked and in clinical use. Additional 24 companies are developing these kind of coronary devices. Most frequently used material is PLLA followed by magnesium.

What is better for predilatation in bioresorbable vascular scaffold implantation: a non-compliant or a compliant balloon?

OBJECTIVE

The bioresorbable vascular scaffold system (BVS) is a fully absorbable vascular treatment system. In this study, we aimed to compare the periprocedural effectiveness and long term results of non-compliant balloon (NCB) and compliant balloon (CB) systems, which are used for predilatation before BVS implantation.

METHODS

One hundred forty-six BVS-treated lesions from 119 patients were retrospectively analyzed in the study. Patients with acute coronary syndrome, stable angina and silent ischemia were included in the study. Lesions and patients were categorized into the NCB and CB groups according to the type of balloon used for predilatation. NCB was implemented on 72 lesions (59 patients) and CB was implemented on 74 lesions (60 patients). The two groups were compared on terms of procedural features and both in-hospital and 1-year clinical follow-up results. Chi-square and independent sample t test were performed for statistical analysis.

RESULTS

There was no significant difference between the two groups in terms of patient characteristics and lesion properties. The number of postdilated lesions was significantly higher in the CB group. Procedure time, fluoroscopy time, and contrast volume were significantly lower in the NCB group. At follow-up, one patient had myocardial infarction in the CB group because of scaffold thrombosis and no mortality was observed.

CONCLUSION

Predilatation with NCB before BVS implantation reduces the need for postdilatation. In addition, use of NCB reduces the procedure time, fluoroscopy time, and contrast volume but had no effect on 1 year clinical follow-up results compared with CB.

Degree of bioresorbable vascular scaffold expansion modulates loss of essential function

Drug-eluting bioresorbable vascular scaffolds (BVSs) have the potential to restore lumen patency, enable recovery of the native vascular environment, and circumvent late complications associated with permanent endovascular devices. To ensure therapeutic effects persist for sufficient times prior to scaffold resorption and resultant functional loss, many factors dictating BVS performance must be identified, characterized and optimized. While some factors relate to BVS design and manufacturing, others depend on device deployment and intrinsic vascular properties. Importantly, these factors interact and cannot be considered in isolation. The objective of this study is to quantify the extent to which degree of radial expansion modulates BVS performance, specifically in the context of modifying device erosion kinetics and evolution of structural mechanics and local drug elution. We systematically varied degree of radial expansion in model BVS constructs composed of poly dl-lactide-glycolide and generated in vitro metrics of device microstructure, degradation, erosion, mechanics and drug release. Experimental data permitted development of computational models that predicted transient concentrations of scaffold-derived soluble species and drug in the arterial wall, thus enabling speculation on the short- and long-term effects of differential expansion. We demonstrate that degree of expansion significantly affects scaffold properties critical to functionality, underscoring its relevance in BVS design and optimization.

STATEMENT OF SIGNIFICANCE

Bioresorbable vascular scaffold (BVS) therapy is beginning to transform the treatment of obstructive artery disease, owing to effective treatment of short term vessel closure while avoiding long term consequences such as in situ, late stent thrombosis - a fatal event associated with permanent implants such as drug-eluting stents. As device scaffolding and drug elution are temporary for BVS, the notion of using this therapy in lieu of existing, clinically approved devices seems attractive. However, there is still a limited understanding regarding the optimal lifetime and performance characteristics of erodible endovascular implants. Several engineering criteria must be met and clinical endpoints confirmed to ensure these devices are both safe and effective. In this manuscript, we sought to establish general principles for the design and deployment of erodible, drug-eluting endovascular scaffolds, with focus on how differential expansion can modulate device performance.

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)

OBJECTIVES

This study sought to describe the frequency and clinical impact of acute scaffold disruption and late strut discontinuity of the second-generation Absorb bioresorbable polymeric vascular scaffolds (Absorb BVS, Abbott Vascular, Santa Clara, California) in the ABSORB (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions) cohort B study by optical coherence tomography (OCT) post-procedure and at 6, 12, 24, and 36 months.

BACKGROUND

Fully bioresorbable scaffolds are a novel approach to treatment for coronary narrowing that provides transient vessel support with drug delivery capability without the long-term limitations of metallic drug-eluting stents. However, a potential drawback of the bioresorbable scaffold is the potential for disruption of the strut network when overexpanded. Conversely, the structural discontinuity of the polymeric struts at a late stage is a biologically programmed fate of the scaffold during the course of bioresorption.

METHODS

The ABSORB cohort B trial is a multicenter single-arm trial assessing the safety and performance of the Absorb BVS in the treatment of 101 patients with de novo native coronary artery lesions. The current analysis included 51 patients with 143 OCT pullbacks who underwent OCT at baseline and follow-up. The presence of acute disruption or late discontinuities was diagnosed by the presence on OCT of stacked, overhung struts or isolated intraluminal struts disconnected from the expected circularity of the device.

RESULTS

Of 51 patients with OCT imaging post-procedure, acute scaffold disruption was observed in 2 patients (3.9%), which could be related to overexpansion of the scaffold at the time of implantation. One patient had a target lesion revascularization that was presumably related to the disruption. Of 49 patients without acute disruption, late discontinuities were observed in 21 patients. There were no major adverse cardiac events associated with this finding except for 1 patient who had a non-ischemia-driven target lesion revascularization.

CONCLUSIONS

Acute scaffold disruption is a rare iatrogenic phenomenon that has been anecdotally associated with anginal symptoms, whereas late strut discontinuity is observed in approximately 40% of patients and could be viewed as a serendipitous OCT finding of a normal bioresorption process without clinical implications. (ABSORB Clinical Investigation, Cohort B [ABSORB B]; NCT00856856).

Fully bioresorbable drug-eluting coronary scaffolds: A review

Following the development of stents, then drug-eluting stents (DES), bioresorbable scaffolds are proposed as a third evolution in coronary angioplasty, aiming to reduce the incidence of restenosis and stent thrombosis and to restore vascular physiology. At least 16 such devices are currently under development, but published clinical data were available for only three of them in September 2014. The first device is Abbott's BVS(®), a poly-L-lactic acid (PLLA)-based everolimus-eluting device, which has been tested in a registry and two non-randomized trials. Clinical results seem close to what is expected from a modern DES, but possibly with more post-procedural side-effects. Two randomized trials versus DES are underway. This device is already marketed in many European countries. The second device is Elixir's DESolve(®), a PLLA-based novolimus-eluting device, which has been evaluated in two single-arm trials. Results are not widely different from those expected from a DES. The third device is Biotronik's DREAMS(®), a metallic magnesium-based paclitaxel-eluting device, which has been assessed in an encouraging single-arm trial; its second version is currently undergoing evaluation in a single-arm trial. The available results suggest that the technological and clinical development of bioresorbable scaffolds is not yet complete: their possible clinical benefits are still unclear compared with third-generation DES; the impact of arterial physiology restoration has to be assessed over the long term; and their cost-effectiveness has to be established. From the perspective of a health technology assessment, there is no compelling reason to hasten the clinical use of these devices before the results of ongoing randomized controlled trials become available.

Lessons learned from acute and late scaffold failures in the ABSORB EXTEND trial

AIMS

Bioresorbable scaffolds are increasingly used in patients with coronary artery disease undergoing percutaneous coronary interventions. ABSORB EXTEND is an ongoing study that will recruit 800 patients. This report evaluates acute and late scaffold failure in the first 450 patients enrolled in ABSORB EXTEND who have completed 12 months follow-up.

METHODS AND RESULTS

Clinical event data from the first 450 patients enrolled in ABSORB EXTEND have demonstrated low rates of ischaemia-driven MACE (4.2%) and target vessel failure (4.7%) at 12 months. There have been seven cases of device failure in this study: three cases of scaffold dislodgement (0.67%) and four cases of subacute or late scaffold thrombosis (0.89%). All scaffold dislodgements occurred in the left circumflex (LCX), and in two cases dislodgement was observed after reinsertion of the same device. Two cases of subacute scaffold thrombosis and two late scaffold thromboses were observed. Two out of four cases of scaffold thrombosis seemed to be related to either premature discontinuation of dual antiplatelet therapy (DAPT) or resistance to clopidogrel.

CONCLUSIONS

This is the first report specifically describing the incidence and the potential mechanisms of scaffold dislodgement and scaffold thrombosis as seen in the ABSORB EXTEND trial.

A 12-month angiographic and optical coherence tomography follow-up after bioresorbable vascular scaffold implantation in patients with ST-segment elevation myocardial infarction

OBJECTIVES

The aim of the study was to evaluate the healing process at 12 months after ABSORB™ bioresorbable vascular scaffold (BVS) implantation in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

There is currently no data on long-term BVS performance in the acute thrombotic setting. The underlying altered plaque pathomorphology may impact the neointima healing pattern, potentially making it different to that observed in stable coronary artery disease (CAD).

METHODS

We have performed an angiographic and optical coherence tomography (OCT) 12-month follow-up of 19 STEMI patients who were treated with a BVS implantation (23 scaffolds). An independent core laboratory performed a paired analysis of the corresponding frames at baseline and follow-up.

RESULTS

At 12 months, the OCT follow-up showed a decrease in the mean lumen area (8.29 ± 1.53 mm(2) vs. 6.82 ± 1.57 mm(2) , P < 0.001), but no significant change in the mean scaffold area (8.49 ± 1.53 mm(2) vs. 8.90 ± 1.51 mm(2) ). Significant decreases in malapposed strut ratio (4.9 ± 8.65% vs. 0.4 ± 1.55%, P < 0.001) and malapposition area (0.29 ± 0.60 mm(2) 0.08 ± 0.32 mm(2) , P = 0.002) were observed. A nonhomogenous proliferation of neointima was revealed with a symmetry index of 0.15 (0.08-0.27), a mean neointima thickness of 203 μm (183-249) and mean neointima area of 2.07 ± 0.51 mm(2) . The quantitative coronary angiography showed late lumen loss of 0.08 ± 0.23 mm and no significant change in the minimal lumen diameter (P = 0.11). There were no major adverse cardiovascular events (MACE), except for one nontarget vessel revascularization.

CONCLUSIONS

The OCT revealed a favorable healing pattern after BVS implantation in a STEMI population.

A bioresorbable everolimus-eluting scaffold versus a metallic everolimus-eluting stent for ischaemic heart disease caused by de-novo native coronary artery lesions (ABSORB II): an interim 1-year analysis of clinical and procedural secondary outcomes from a randomised controlled trial

BACKGROUND

Despite rapid dissemination of an everolimus-eluting bioresorbable scaffold for treatment for coronary artery disease, no data from comparisons with its metallic stent counterpart are available. In a randomised controlled trial we aimed to compare an everolimus-eluting bioresorbable scaffold with an everolimus-eluting metallic stent. Here we report secondary clinical and procedural outcomes after 1 year of follow-up.

METHODS

In a single-blind, multicentre, randomised trial, we enrolled eligible patients aged 18-85 years with evidence of myocardial ischaemia and one or two de-novo native lesions in different epicardial vessels. We randomly assigned patients in a 2:1 ratio to receive treatment with an everolimus-eluting bioresorbable scaffold (Absorb, Abbott Vascular, Santa Clara, CA, USA) or treatment with an everolimus-eluting metallic stent (Xience, Abbott Vascular, Santa Clara, CA, USA). Randomisation was stratified by diabetes status and number of planned target lesions. The co-primary endpoints of this study are vasomotion (change in mean lumen diameter before and after nitrate administration at 3 years) and difference between minimum lumen diameter (after nitrate administration) after the index procedure and at 3 years. Secondary endpoints were procedural performance assessed by quantitative angiography and intravascular ultrasound; composite clinical endpoints based on death, myocardial infarction, and coronary revascularisation; device and procedural success; and angina status assessed by the Seattle Angina Questionnaire and exercise testing at 6 and 12 months. Cumulative angina rate based on adverse event reporting was analysed post hoc. This trial is registered at ClinicalTrials.gov, number NCT01425281.

FINDINGS

Between Nov 28, 2011, and June 4, 2013, we enrolled 501 patients and randomly assigned them to the bioresorbable scaffold group (335 patients, 364 lesions) or the metallic stent group (166 patients, 182 lesions). Dilatation pressure and balloon diameter at the highest pressure during implantation or postdilatation were higher and larger in the metallic stent group, whereas the acute recoil post implantation was similar (0.19 mm for both, p=0.85). Acute lumen gain was lower for the bioresorbable scaffold by quantitative coronary angiography (1.15 mm vs 1.46 mm, p<0.0001) and quantitative intravascular ultrasound (2.85 mm(2)vs 3.60 mm(2), p<0.0001), resulting in a smaller lumen diameter or area post procedure. At 1 year, however, cumulative rates of first new or worsening angina from adverse event reporting were lower (72 patients [22%] in the bioresorbable scaffold group vs 50 [30%] in the metallic stent group, p=0.04), whereas performance during maximum exercise and angina status by SAQ were similar. The 1-year composite device orientated endpoint was similar between the bioresorbable scaffold and metallic stent groups (16 patients [5%] vs five patients [3%], p=0.35). Three patients in the bioresorbable scaffold group had definite or probable scaffold thromboses (one definite acute, one definite sub-acute, and one probable late), compared with no patients in the metallic stent group. There were 17 (5%) major cardiac adverse events in the bioresorbable scaffold group compared with five (3%) events in the metallic stent group, with the most common adverse events being myocardial infarction (15 cases [4%] vs two cases [1%], respectively) and clinically indicated target-lesion revascularisation (four cases [1%] vs three cases [2%], respectively).

INTERPRETATION

The everolimus-eluting bioresorbable scaffold showed similar 1-year composite secondary clinical outcomes to the everolimus-eluting metallic stent.

FUNDING

Abbott Vascular.

Dynamics of vessel wall changes following the implantation of the absorb everolimus-eluting bioresorbable vascular scaffold: a multi-imaging modality study at 6, 12, 24 and 36 months

AIMS

To assess observations with multimodality imaging of the Absorb bioresorbable everolimus-eluting vascular scaffold performed in two consecutive cohorts of patients who were serially investigated either at 6 and 24 months or at 12 and 36 months.

METHODS AND RESULTS

In the ABSORB multicentre single-arm trial, 45 patients (cohort B1) and 56 patients (cohort B2) underwent serial invasive imaging, specifically quantitative coronary angiography (QCA), intravascular ultrasound (IVUS), radiofrequency backscattering (IVUS-VH) and optical coherence tomography (OCT). Between one and three years, late luminal loss remained unchanged (6 months: 0.19 mm, 1 year: 0.27 mm, 2 years: 0.27 mm, 3 years: 0.29 mm) and the in-segment angiographic restenosis rate for the entire cohort B (n=101) at three years was 6%. On IVUS, mean lumen, scaffold, plaque and vessel area showed enlargement up to two years. Mean lumen and scaffold area remained stable between two and three years whereas significant reduction in plaque behind the struts occurred with a trend toward adaptive restrictive remodelling of EEM. Hyperechogenicity of the vessel wall, a surrogate of the bioresorption process, decreased from 23.1% to 10.4% with a reduction of radiofrequency backscattering for dense calcium and necrotic core. At three years, the count of strut cores detected on OCT increased significantly, probably reflecting the dismantling of the scaffold; 98% of struts were covered. In the entire cohort B (n=101), the three-year major adverse cardiac event rate was 10.0% without any scaffold thrombosis.

CONCLUSIONS

The current investigation demonstrated the dynamics of vessel wall changes after implantation of a bioresorbable scaffold, resulting at three years in stable luminal dimensions, a low restenosis rate and a low clinical major adverse cardiac events rate.

CLINICAL TRIAL REGISTRATION INFORMATION

http://www.clinicaltrials.gov/ct2/show/NCT00856856.