Very Late Thrombosis After Bioresorbable Scaffolds

Endovascular Drug Delivery

Drug-eluting stents (DES) and balloons revolutionize atherosclerosis treatment by targeting hyperplastic tissue responses through effective local drug delivery strategies. This review examines approved and emerging endovascular devices, discussing drug release mechanisms and their impacts on arterial drug distribution. It emphasizes the crucial role of drug delivery in modern cardiovascular care and highlights how device technologies influence vascular behavior based on lesion morphology. The future holds promise for lesion-specific treatments, particularly in the superficial femoral artery, with recent CE-marked devices showing encouraging results. Exciting strategies and new patents focus on local drug delivery to prevent restenosis, shaping the future of interventional outcomes. In summary, as we navigate the ever-evolving landscape of cardiovascular intervention, it becomes increasingly evident that the future lies in tailoring treatments to the specific characteristics of each lesion. By leveraging cutting-edge technologies and harnessing the potential of localized drug delivery, we stand poised to usher in a new era of precision medicine in vascular intervention.

5-Year Outcomes After Bioresorbable Coronary Scaffolds Implanted With Improved Technique

BACKGROUND

Bioresorbable vascular scaffolds (BVS) were designed to improve late event-free survival compared with metallic drug-eluting stents. However, initial trials demonstrated worse early outcomes with BVS, in part due to suboptimal technique. In the large-scale, blinded ABSORB IV trial, polymeric everolimus-eluting BVS implanted with improved technique demonstrated noninferior 1-year outcomes compared with cobalt chromium everolimus-eluting stents (CoCr-EES).

OBJECTIVES

This study sought to evaluate the long-term outcomes from the ABSORB IV trial.

METHODS

We randomized 2,604 patients at 147 sites with stable or acute coronary syndromes to BVS with improved technique vs CoCr-EES. Patients, clinical assessors, and event adjudicators were blinded to randomization. Five-year follow-up was completed.

RESULTS

Target lesion failure at 5 years occurred in 216 (17.5%) patients assigned to BVS and 180 (14.5%) patients assigned to CoCr-EES (P = 0.03). Device thrombosis within 5 years occurred in 21 (1.7%) BVS and 13 (1.1%) CoCr-EES patients (P = 0.15). Event rates were slightly greater with BVS than CoCr-EES through 3-year follow-up and were similar between 3 and 5 years. Angina, also centrally adjudicated, recurred within 5 years in 659 patients (cumulative rate 53.0%) assigned to BVS and 674 (53.3%) patients assigned to CoCr-EES (P = 0.63).

CONCLUSIONS

In this large-scale, blinded randomized trial, despite the improved implantation technique, the absolute 5-year rate of target lesion failure was 3% greater after BVS compared with CoCr-EES. The risk period for increased events was limited to 3 years, the time point of complete scaffold bioresorption; event rates were similar thereafter. Angina recurrence after intervention was frequent during 5-year follow-up but was comparable with both devices.(Absorb IV Randomized Controlled Trial; NCT02173379).

Four-Year Outcomes of Left Main Percutaneous Coronary Intervention with a Bioresorbable Scaffold in the Circumflex Ostium

Objectives. The study aimed to investigate the long-term outcomes of a double stent scaffold strategy in patients with left main (LM) bifurcation lesions involving the ostium of the left circumflex artery (LCX), utilizing a drug-eluting stent (DES) in the LM extending into the left anterior descending artery (LAD) and a bioresorbable vascular scaffold (BVS) in the LCX ostium. Background. The high occurrence of in-stent restenosis of the LCX ostium is the major limitation of percutaneous coronary intervention (PCI) for LM lesions with a two-stent strategy. Methods. This was a single-center, prospective, single-arm study of 46 consecutively enrolled patients with a stable coronary artery disease and significant unprotected LM distal bifurcation disease. Patients underwent imaging-guided PCI using DES in the LM-LAD and BVS in the LCX using a T-stent or mini-crush technique. The primary outcome at four years was the composite of death, myocardial infarction, stroke, and target lesion revascularization (TLR). Results. At four years, the primary outcome was identified in 9 patients (19.6%). All events were TLRs except one myocardial infarction due to BVS thrombosis. Seven of the eight TLRs were a result of side branch BVS restenosis. Univariate predictors of the 4-year outcome were higher LDL cholesterol and BVS size ≤2.5 mm. On multivariate analysis, LCX lesion preparation with a cutting balloon and post-procedure use of intravascular ultrasound for optimization were found to be independent protective factors of MACE. Conclusions. In selected patients with LM distal bifurcation disease, an imaging-guided double stent scaffold strategy with DES in the LM and BVS in the LCX ostium was technically successful in all patients and was reasonably safe and effective for four years.

An experimental investigation into the physical, thermal and mechanical degradation of a polymeric bioresorbable scaffold

This study presents a comprehensive evaluation of the mechanical, micro-mechanical and physical properties of Reva Medical Fantom Encore Bioresorbable Scaffolds (BRS) subjected to a thermally-accelerated degradation protocol. The Fantom Encore BRS were immersed in phosphate buffered saline solution at 50 °C for 112 days with radial compression testing, nanoindentation, differential scanning calorimetry, gel permeation chromatography and mass loss characterisation performed at consecutive time points. In the initial stages of degradation (Days 0-21), the Fantom Encore BRS showed increases in radial strength and stiffness, despite a substantial reduction in in molecular weight, with a slight increase in the melt temperature also observed. In the second phase (Days 35-54), the radial strength of the BRS samples were maintained despite a continued loss in molecular weight. However, during this phase, the ductility of the stent showed a reduction, with stent fracture occurring earlier in the crimp process and with lower amounts of plastic deformation evident under visual examination post-fracture. In the final phase (Days 63-112), the load-bearing capacity of the Fantom Encore BRS showed continued reduction, with decreases in radial stiffness and strength, and drastic reduction in the work-to-fracture of the devices. Throughout each phase, there was a steady increase in the relative crystallinity, with limited mass loss until day 112 and only minor changes in glass transition and melt temperatures. Limited changes were observed in nano-mechanical properties, with measured local elastic moduli and hardness values remaining largely similar throughout degradation. Given that the thermally-accelerated in vitro conditions represented a four-fold acceleration of physiological conditions, these results suggest that the BRS scaffolds could exhibit substantially brittle behaviour after ∼ one year of implantation.

Vascular Lesion-Specific Drug Delivery Systems: JACC State-of-the-Art Review

Drug delivery is central to modern cardiovascular care, where drug-eluting stents, bioresorbable scaffolds, and drug-coated balloons all aim to restore perfusion while inhibiting exuberant healing. The promise and enthusiasm of these devices has in some cases exceeded demonstration of efficacy and even understanding of driving mechanisms. The authors review the means of drug delivery in each device, outlining how the technologies affect vascular behavior. They focus on how drug retention and response are governed by lesion morphology: lipid displacing drug-specific binding sites, calcium inhibiting diffusion, blocking thrombi or promoting luminal washout, and vascular healing steering hyperplastic developments. In this regard, the authors outline the fundamental impact of vascular structure on drug delivery and review the development of contemporary and future devices for coronary and peripheral intervention. They look toward a future where incorporating information on lesion distribution is central to therapeutic success and envision a transition toward lesion-specific treatment for improved interventional outcomes.

Physical and mechanical degradation behaviour of semi-crystalline PLLA for bioresorbable stent applications

This study presents a systematic evaluation of the physical, thermal and mechanical performance of medical-grade semi-crystalline PLLA undergoing thermally-accelerated degradation. Samples were immersed in phosphate-buffered saline solution at 50 °C for 112 days and mass loss, molecular weight, thermal properties, degree of crystallinity, FTIR and Raman spectra, tensile elastic modulus, yield stress and failure stress/strain were evaluated at consecutive time points. Samples showed a consistent reduction in molecular weight and melting temperature, a consistent increase in percent crystallinity and limited changes in glass transition temperature and mass loss. At day 49, a drastic reduction in tensile failure strain was observed, despite the fact that elastic modulus, yield and tensile strength of samples were maintained. Brittleness increase was followed by rapid increase in degradation rate. Beyond day 70, samples became too brittle to test indicating substantial deterioration of their load-bearing capacity. This study also presents a computational micromechanics framework that demonstrates that the elastic modulus of a semi-crystalline polymer undergoing degradation can be maintained, despite a reducing molecular weight through compensatory increases in percent crystallinity. This study presents novel insight into the relationship between physical properties and mechanical performance of medical-grade PLLA during degradation and could have important implications for design and development of bioresorbable stents for vascular applications.

Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents

Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.

Stent-Related Adverse Events >1 Year After Percutaneous Coronary Intervention

BACKGROUND

The majority of stent-related major adverse cardiovascular events (MACE) after percutaneous coronary intervention (PCI) are believed to occur within the first year. Very-late (>1-year) stent-related MACE have not been well described.

OBJECTIVES

The purpose of this study was to assess the frequency and predictors of very-late stent-related events or MACE by stent type.

METHODS

Individual patient data from 19 prospective, randomized metallic stent trials maintained at a leading academic research organization were pooled. Very-late MACE (a composite of cardiac death, myocardial infarction [MI], or ischemia-driven target lesion revascularization [ID-TLR]), and target lesion failure (cardiac death, target-vessel MI, or ID-TLR) were assessed within year 1 and between 1 and 5 years after PCI with bare-metal stents (BMS), first-generation drug-eluting stents (DES1) and second-generation drug-eluting stents (DES2). A network meta-analysis was performed to evaluate direct and indirect comparisons.

RESULTS

Among 25,032 total patients, 3,718, 7,934, and 13,380 were treated with BMS, DES1, and DES2, respectively. MACE rates within 1 year after PCI were progressively lower after treatment with BMS versus DES1 versus DES2 (17.9% vs. 8.2% vs. 5.1%, respectively, p < 0.0001). Between years 1 and 5, very-late MACE occurred in 9.4% of patients (including 2.9% cardiac death, 3.1% MI, and 5.1% ID-TLR). Very-late MACE occurred in 9.7%, 11.0%, and 8.3% of patients treated with BMS, DES1, and DES2, respectively (p < 0.0001), linearly increasing between 1 and 5 years. Similar findings were observed for target lesion failure in 19,578 patients from 12 trials. Findings were confirmed in the network meta-analysis.

CONCLUSIONS

In this large-scale, individual patient data pooled study, very-late stent-related events occurred between 1 and 5 years after PCI at a rate of ∼2%/year with all stent types, with no plateau evident. New approaches are required to improve long-term outcomes after PCI.

Final report of the 5-year clinical outcomes of the XINSORB bioresorbable sirolimus-eluting scaffold in the treatment of single de novo coronary lesions in a first-in-human study

Background

We aimed to report the 5-year outcomes of XINSORB bioresorbable sirolimus-eluting scaffolds in the treatment of single de novo coronary lesions in a first-in-human (FIM) study. This is the final report of the long-term clinical outcomes of the study. Recent studies have shown that bioresorbable scaffolds (BRSs) increase the risks of late target lesion failure (TLF) and thrombosis.

Methods

In this prospective, single-arm study, eligible patients with single de novo coronary lesions were enrolled and treated with XINSORB scaffolds. The scaffolds measured 3.0 mm in diameter and 12, 15, and 18 mm in length. The clinical endpoints included TLF [cardiac death, target vessel-related myocardial infarction (TV-MI), or ischaemia-driven target lesion revascularization (ID-TLR)], its components, major adverse cardiac events (MACE), and scaffold thrombosis.

Results

From September 2013 to January 2014, 30 patients were enrolled and treated with XINSORB scaffolds. The procedure had a 100% success rate. None of the patients died during the 5 years of follow-up. The primary endpoint of TLF occurred in 4 patients (13.3%). Six patients were recanalized by intervention, including 4 by ID-TLR. The rate of MACE was 16.7% (5/30). One very late case of scaffold thrombosis was recorded, which led to TV-MI. No more cases of thrombosis were recorded beyond 2 years of follow-up. The rates of clinical endpoints remained steady with no changes after 3 years of follow-up.

Conclusions

Considering that this FIM study was launched at an early stage of the BRS era and without optimal implantation techniques, the clinical outcomes of TLF during the 5-year follow-up were acceptable. The rate of thrombosis was relatively low.

Time-Varying Outcomes With the Absorb Bioresorbable Vascular Scaffold During 5-Year Follow-up: A Systematic Meta-analysis and Individual Patient Data Pooled Study

Importance

Bioresorbable scaffolds were designed to provide clinical benefits after their complete bioresorption. Prior studies demonstrated early risks with the Absorb polymeric bioresorbable vascular scaffold (BVS). Whether this risk profile changes over time during the course of its bioresorption is unknown.

Objective

To examine outcomes of the first-generation BVS before and after 3 years, the point of its complete bioresorption in animals.

Data Sources

We searched MEDLINE and the Cochrane database, conference proceedings, and public websites for relevant studies.

Study Selection

Eligible studies were randomized clinical trials of BVS vs metallic drug-eluting stents in patients with coronary artery disease with at least 5-year follow-up. Four trials of BVS vs everolimus-eluting stents (EES) with 3384 patients met criteria.

Data Extraction and Synthesis

Individual patient data from the 4 trials were pooled, and summary-level meta-analysis was performed.

Main Outcomes and Measures

The major effectiveness and safety measures were target lesion failure (TLF; cardiac death, target vessel-related myocardial infarction, or ischemia-driven target lesion revascularization) and device thrombosis. Outcomes were examined through 5-year follow-up and between 0 to 3 and 3 to 5 years.

Results

Mean age for the 3384 patients was 62.8 years; 2452 patients were men (72.5%), and diabetes was present in 1020 patients (30.2%). Through 5-year follow-up, treatment with BVS compared with EES was associated with higher rates of TLF (14.9% vs 11.6%; HR, 1.26; 95% CI, 1.03-1.54; P = .03) and device thrombosis (2.5% vs 0.8%; HR, 2.87; 95% CI, 1.46-5.65; P = .002). Target lesion failure occurred in 11.6% of BVS-treated patients vs 7.9% of EES-treated patients between 0 to 3 years (HR, 1.42; 95% CI, 1.12-1.80), and 4.3% of BVS-treated patients vs 4.5% of EES-treated patients between 3 to 5 years (HR, 0.92; 95% CI, 0.64-1.31) (P for interaction = .046). Device thrombosis occurred in 2.4% of BVS-treated patients vs 0.6% of EES-treated patients between 0 to 3 years (HR, 3.86; 95% CI, 1.75-8.50) and 0.1% of BVS-treated patients vs 0.3% of EES-treated patients between 3 to 5 years (HR, 0.44; 95% CI, 0.07-2.70) (P for interaction = .03). These results were consistent by spline analysis and after multiple imputation and multivariable analysis.

Conclusions and Relevance

The period of excess risk for the first-generation Absorb BVS ends at 3 years. These data provide mechanistic insights into the timing of adverse events after BVS and identify the hurdles to be overcome for bioresorbable technology to be accepted as a valid alternative for patients with coronary artery disease.

Trial Registration

ClinicalTrials.gov identifiers: NCT01751906, NCT01844284, NCT01923740, and NCT01425281.

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

•

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

•

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

•

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

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

Clinical, Angiographic, and Procedural Correlates of Very Late Absorb Scaffold Thrombosis: Multistudy Registry Results

OBJECTIVES

The aim of this study was to identify independent correlates of very late scaffold thrombosis (VLST) from an analysis of consecutively treated patients from 15 multicenter studies.

BACKGROUND

Recent analyses suggest an increased risk for VLST with the Absorb Bioresorbable Vascular Scaffold compared with drug-eluting stents, but insights as to correlates of risk are limited.

METHODS

A total of 55 patients were identified with scaffold thrombosis. They were matched 2:1 with control subjects selected randomly from patients without thrombosis from the same study. Quantitative coronary angiography was available for 96.4% of patients. Multiple logistic and Cox regression analysis were used to identify significant independent outcome correlates from 6 pre-specified characteristics.

RESULTS

Patients had scaffold thrombosis at a median of 20 months (interquartile range: 17 to 27 months). Control subjects were followed for 36 months (interquartile range: 24 to 38 months). For the combined groups, reference vessel diameter (RVD) was 2.84 ± 0.50 mm, scaffold length was 26 ± 16 mm, and post-dilatation was performed in 56%. Univariate correlates of thrombosis were smaller nominal scaffold/RVD ratio (linear p = 0.001; ratio <1.18:1; odds ratio: 7.5; p = 0.002) and larger RVD (linear p = 0.001; >2.72 mm; odds ratio: 3.4; p = 0.001). Post-dilatation at ≥16 atm, post-dilatation balloon/scaffold ratio, final percentage stenosis, and dual antiplatelet therapy were not correlated with VLST. Only scaffold/RVD ratio remained a significant independent correlate of VLST (p = 0.001), as smaller ratio was correlated with RVD (p < 0.001). Post hoc analysis of 8 other potential covariates revealed no other correlates of outcome.

CONCLUSIONS

In the present analysis, the largest to date of its type, relative scaffold undersizing was the strongest determinant of VLST. Given current understanding of "scaffold dismantling," this finding likely has ramifications for all bioresorbable scaffolds.

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.

In vitro mechanical behavior and in vivo healing response of a novel thin-strut ultrahigh molecular weight poly-l-lactic acid sirolimus-eluting bioresorbable coronary scaffold in normal swine

BACKGROUND

New generation bioresorbable scaffolds (BRS) promise to improve the outcomes of current generation BRS technologies by decreasing wall thickness while maintaining structural strength. This study aimed to compare the biomechanical behavior and vascular healing profile of a novel thin-walled (98 μm) sirolimus-eluting ultrahigh molecular weight BRS (Magnitude, Amaranth Medical) to the Absorb everolimus-eluting bioresorbable vascular scaffold (Abbott Vascular).

METHODS AND RESULTS

In vitro biomechanical testing showed lower number of fractures on accelerated cycle testing over time (at 21K cycles = 20.0 [19.0-21.0] in Absorb versus 0.0 [0.0-1.0] in Magnitude-BRS). Either Magnitude (n = 43) or Absorb (n = 22) was implanted in 65 coronary segments of 22 swine. Scaffold strut's coverage was evaluated using serial optical coherence tomography (OCT) analysis. At 14 days, Magnitude-BRS demonstrated a higher percentage of embedded struts (97.7% [95.3, 100.0] compared to Absorb (57.2% [48.0, 76.0], p = 0.003) and lower percentage of uncovered struts (0.0% [0.0, 0.0] versus Absorb 5.5% [2.6, 7.7], p = 0.02). Also, it showed a lower percent late recoil (-1.02% [-4.11, 3.21] versus 4.42% [-1.10, 8.74], p = 0.04) at 28 days. Histopathology revealed comparable neointimal proliferation and vascular healing responses between two devices up to 180 days.

CONCLUSION

A new generation thin walled (98-μm) Magnitude-BRS displayed a promising biomechanical behavior and strut healing profile compared to Absorb at the experimental level. This new generation BRS platform has the potential to improve the clinical outcomes shown by the current generation BRS.

Blinded outcomes and angina assessment of coronary bioresorbable scaffolds: 30-day and 1-year results from the ABSORB IV randomised trial

BACKGROUND

Previous studies showed more adverse events with coronary bioresorbable vascular scaffolds (BVS) than with metallic drug-eluting stents (DES), although in one randomised trial angina was reduced with BVS. However, these early studies were unmasked, lesions smaller than intended for the scaffold were frequently enrolled, implantation technique was suboptimal, and patients with myocardial infarction, in whom BVS might be well suited, were excluded.

METHODS

In the active-controlled, blinded, multicentre, randomised ABSORB IV trial, patients with stable coronary artery disease or acute coronary syndromes aged 18 years or older were recruited from 147 hospitals in five countries (the USA, Germany, Australia, Singapore, and Canada). Enrolled patients were randomly assigned (1:1) to receive polymeric everolimus-eluting BVS (Absorb; Abbott Vascular, Santa Clara, CA, USA) with optimised implantation technique or cobalt-chromium everolimus-eluting stents (EES; Xience; Abbott Vascular, Santa Clara, CA, USA). Randomisation was stratified by diabetic status, whether patients would have been eligible for enrolment in the previous ABSORB III trial, and site. Patients and clinical assessors were masked to randomisation. The primary endpoint was target lesion failure (cardiac death, target vessel myocardial infarction, or ischaemia-driven target lesion revascularisation) at 30 days, tested for non-inferiority with a 2·9% margin for the risk difference. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT02173379, and is closed to accrual.

FINDINGS

Between Aug 15, 2014, and March 31, 2017, we screened 18 722 patients for eligibility, 2604 of whom were enrolled. 1296 patients were assigned to BVS, and 1308 patients were assigned to EES. Follow-up data at 30 days and 1 year, respectively, were available for 1288 and 1254 patients with BVS and for 1303 and 1272 patients with EES. Biomarker-positive acute coronary syndromes were present in 622 (24%) of 2602 patients, and, by angiographic core laboratory analysis, 78 (3%) of 2893 of lesions were in very small vessels. Target lesion failure at 30 days occurred in 64 (5·0%) patients assigned to BVS and 48 (3·7%) patients assigned to EES (difference 1·3%, upper 97·5% confidence limit 2·89; one-sided p_{non-inferiority}=0·0244). Target lesion failure at 1 year occurred in 98 (7·8%) patients assigned to BVS and 82 (6·4%) patients assigned to EES (difference 1·4%, upper 97·5% confidence limit 3·4; one-sided p_{non-inferiority}=0·0006). Angina, adjudicated by a central events committee at 1 year, occurred in 270 (20·3%) patients assigned to BVS and 274 (20·5%) patients assigned to EES (difference -0·3%, 95% CI -3·4% to 2·9%; one-sided p_{non-inferiority}=0·0008; two-sided p_superiority=0·8603). Device thrombosis within 1 year occurred in nine (0·7%) patients assigned to BVS and four (0·3%) patients assigned to EES (p=0·1586).

INTERPRETATION

Polymeric BVS implanted with optimised technique in an expanded patient population resulted in non-inferior 30-day and 1-year rates of target lesion failure and angina compared with metallic DES.

FUNDING

Abbott Vascular.

Long-term outcome of first 300 implanted Absorb bioresorbable vascular scaffolds in an all-comers Middle East population

Objectives

To evaluate long-term clinical outcomes of the Absorb bioresorbable vascular scaffold (BVS) system (Abbott Vascular) in an all-comers Middle East population.

Methods

This prospective registry study included an initial set of patients with coronary lesions treated using Absorb BVS. Patients were followed for target vessel failure (TVF) including cardiac death, target vessel myocardial infarction (MI), and target lesion revascularization.

Results

A total of 217 patients (age, 55 ± 11 years; male, 169) with 300 treated lesions were included (median follow-up, 36 months [range, 26–41 months]; complete follow-up, 201 patients). Diabetes mellitus and acute coronary syndrome were present in 50% and 57% of patients, respectively. TVF rate was 32/201 (15.9%), including cardiac death in 10 (5%), target vessel MI in 13 (6.5%), and target lesion revascularization in 22 patients (10.9%). Definite or probable device thrombosis occurred in 11/201 patients (5.5%). TVF was associated with heart failure, worse ejection fraction, multi-vessel BVS, multi BVS in lesion, and total BVS length >50 mm.

Conclusions

Long-term outcome following Absorb BVS implantation in a population with high prevalence of high-risk and complex patients is acceptable, but heart failure, worse ejection fraction, and multi-vessel or long BVS implantation were associated with worse outcomes.

Meta-Analysis Comparing Outcomes After Everolimus-Eluting Bioresorbable Vascular Scaffolds Versus Everolimus-Eluting Metallic Stents in Patients with Acute Coronary Syndromes

Acute coronary syndromes (ACS) may represent an intriguing clinical scenario for implantation of bioresorbable vascular scaffold (BRS). Nevertheless, the knowledge about the performance of these devices in patients with ACS is limited. Therefore, we performed a meta-analysis of clinical studies aiming to assess the safety and efficacy of everolimus-eluting-BRS versus everolimus-eluting-metallic stents (EES) in ACS patients undergoing percutaneous coronary intervention. Six studies enrolling 2,318 patients were included and analyzed for the risk of primary safety outcome (stent or scaffold thrombosis [ST/ScT]), primary efficacy outcome (target lesion revascularisation [TLR]), and secondary outcomes (myocardial infarction, cardiac death, all-cause death). Median follow-up was 9.5 (6 to 19.5) months. Patients treated with BRS had a significantly higher risk of definite ST/ScT compared with those receiving EES (2.3% vs 1.08%, odds ratio [OR] 2.22, 95% confidence interval [CI] 1.10 to 4.45, p = 0.03, I2 = 0%). Similarly, the risk of TLR was significantly higher in the BRS compared with EES group (3.5% vs 2.5%, OR 1.79, 95% CI 1.02 to 3.16, p = 0.04, I2 = 0%). When TLRs due to thrombosis were excluded, the difference in risk estimates between the 2 groups was no longer significant (OR 1.19, 95% CI 0.48 to 2.98, p = 0.71, I2 = 25%). Risk for secondary endpoints did not differ between the 2 groups. Results were confirmed when clinical and procedural variables were tested as potential effect modifiers in the meta-regression analysis for both primary endpoints. In conclusion, compared with those receiving EES, patients with ACS treated with BRS had increased risk of definite device thrombosis and TLR at mid-term follow-up.

Comparative Characterization of Biomechanical Behavior and Healing Profile of a Novel Ultra-High-Molecular-Weight Amorphous Poly-l-Lactic Acid Sirolimus-Eluting Bioresorbable Coronary Scaffold

BACKGROUND

Clinically available bioresorbable scaffolds (BRS) rely on polymer crystallinity to achieve mechanical strength resulting in limited overexpansion capabilities and structural integrity when exposed to high-loading conditions. We aimed to evaluate the biomechanical behavior and vascular healing profile of a novel, sirolimus-eluting, high-molecular-weight, amorphous poly-l-lactic acid-based BRS (Amaranth BRS).

METHODS AND RESULTS

In vitro biomechanical testing was performed under static and cyclic conditions. A total of 99 devices (65 Amaranth BRS versus 34 Absorb bioresorbable vascular scaffold [BVS]) were implanted in 99 coronary arteries of 37 swine for pharmacokinetics and healing evaluation at various time points. In the Absorb BVS, the number of fractures per scaffold seen on light microscopy was 6.0 (5.0-10.5) when overexpanded 1.0 mm above nominal values (≈34%). No fractures were observed in the Amaranth BRS group at 1.3 mm above nominal values (≈48% overexpansion). The number of fractures was higher in the Absorb BVS on accelerated cycle testing over time (at 24K cycles=5.0 [5.0-9.0] Absorb BVS versus 0.0 [0.0-0.5] Amaranth BRS). Approximately 90% of sirolimus was found to be eluted by 90 days. Optical coherence tomography analysis demonstrated lower percentages of late scaffold recoil in the Amaranth BRS at 3 months (Amaranth BRS=-10±16.1% versus Absorb BVS=10.7±13.2%; P=0.004). Histopathology analysis revealed comparable levels of vascular healing and inflammatory responses between both BRSs up to 6 months.

CONCLUSIONS

New-generation high-molecular-weight amorphous poly-l-lactic acid scaffolds have the potential to improve the clinical performance of BRS and provide the ideal platform for the future miniaturization of the technology.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

3-Year Clinical Outcomes With Everolimus-Eluting Bioresorbable Coronary Scaffolds: The ABSORB III Trial

BACKGROUND

The Absorb everolimus-eluting poly-L-lactic acid-based bioresorbable vascular scaffold (BVS) provides early drug delivery and mechanical support functions similar to metallic drug-eluting stents (DES), followed by complete bioresorption in approximately 3 years with recovery of vascular structure and function. The ABSORB III trial demonstrated noninferior rates of target lesion failure (cardiac death, target vessel myocardial infarction [TVMI], or ischemia-driven target lesion revascularization) at 1 year in 2,008 patients with coronary artery disease randomized to BVS versus cobalt-chromium everolimus-eluting stents (EES).

OBJECTIVES

This study sought to assess clinical outcomes through 3 years following BVS implantation.

METHODS

Clinical outcomes from the ABSORB III trial were analyzed by randomized treatment assignment cumulative through 3 years, and between 1 and 3 years.

RESULTS

The primary composite endpoint of target lesion failure through 3 years occurred in 13.4% of BVS patients and 10.4% of EES patients (p = 0.06), and between 1 and 3 years in 7.0% versus 6.0% of patients, respectively (p = 0.39). TVMI through 3 years was increased with BVS (8.6% vs. 5.9%; p = 0.03), as was device thrombosis (2.3% vs. 0.7%; p = 0.01). In BVS-assigned patients, treatment of very small vessels (those with quantitatively determined reference vessel diameter <2.25 mm) was an independent predictor of 3-year TLF and scaffold thrombosis.

CONCLUSIONS

In the ABSORB III trial, 3-year adverse event rates were higher with BVS than EES, particularly TVMI and device thrombosis. Longer-term clinical follow-up is required to determine whether bioresorption of the polymeric scaffold will influence patient prognosis. (ABSORB III Randomized Controlled Trial [RCT] [ABSORB-III]; NCT01751906).

Three-Year Outcomes With the Absorb Bioresorbable Scaffold: Individual-Patient-Data Meta-Analysis From the ABSORB Randomized Trials

BACKGROUND

The Absorb bioresorbable vascular scaffold (BVS) completely resorbs within 3 years after coronary artery implantation. The safety and effectiveness of BVS through this critical 3-year period have not been characterized.

METHODS

We performed an individual-patient-data pooled meta-analysis of the 4 randomized ABSORB trials in which 3389 patients with coronary artery disease were randomly assigned to everolimus-eluting Absorb BVS (n=2164) or cobalt-chromium everolimus-eluting stents (n=1225). The primary efficacy outcome measure was target lesion failure (cardiac mortality, target vessel myocardial infarction, or ischemia-driven target lesion revascularization), and the primary safety outcome measure was device thrombosis.

RESULTS

BVS compared with cobalt-chromium everolimus-eluting stents resulted in higher 3-year rates of target lesion failure (11.7% versus 8.1%; risk ratio [RR], 1.38; 95% confidence interval [CI], 1.10-1.73; P=0.006), driven by greater target vessel myocardial infarction (7.8% versus 4.2%; RR, 1.72; 95% CI, 1.26-2.35; P=0.0006) and ischemia-driven target lesion revascularization (6.6% versus 4.4%; RR, 1.44; 95% CI, 1.05-1.98; P=0.02), with comparable cardiac mortality (1.1% versus 1.1%; RR, 0.93; 95% CI, 0.47-1.88; P=0.85). Device thrombosis rates through 3 years were also higher with BVS (2.4% versus 0.6%; RR, 3.71; 95% CI, 1.70-8.11; P=0.001). Between 1 and 3 years, target lesion failure rates (6.1% versus 3.9%; P=0.02) and device thrombosis rates (1.1% versus 0.0%; P<0.0001) were higher with BVS than cobalt-chromium everolimus-eluting stents.

CONCLUSIONS

In the present individual-patient-data pooled meta-analysis of the ABSORB trials, BVS was associated with increased rates of target lesion failure and device thrombosis between 1 and 3 years and cumulatively through 3 years of follow-up compared with everolimus-eluting stents.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifiers: NCT01751906, NCT01844284, NCT01923740, and NCT01425281.

2-year outcomes with the Absorb bioresorbable scaffold for treatment of coronary artery disease: a systematic review and meta-analysis of seven randomised trials with an individual patient data substudy

BACKGROUND

Bioresorbable vascular scaffolds (BVS) offer the potential to improve long-term outcomes of percutaneous coronary intervention after their complete bioresorption. Randomised trials have shown non-inferiority between BVS and metallic drug-eluting stents at 1 year in composite safety and effectiveness outcomes, although some increases in rates of target vessel-related myocardial infarction and device thrombosis were identified. Outcomes of BVS following the first year after implantation are unknown. We sought to ascertain whether BVS are as safe and effective as drug-eluting stents within 2 years after implantation and between 1 and 2 years.

METHODS

We did a systematic review and meta-analysis of randomised trials in which patients were randomly assigned to everolimus-eluting Absorb BVS or metallic everolimus-eluting stents (EES) and followed up for at least 2 years. We searched MEDLINE, the Cochrane database, TCTMD, ClinicalTrials.gov, Clinical Trial Results, CardioSource, and abstracts and presentations from major cardiovascular meetings up to April 1, 2017, to identify relevant studies. The primary efficacy outcome measure was the device-oriented composite endpoint (cardiac mortality, target vessel-related myocardial infarction, or ischaemia-driven target lesion revascularisation) and the primary safety outcome measure was definite or probable device thrombosis. Individual patient data from the four ABSORB trials were used for landmark and subgroup analysis and multivariable modelling.

FINDINGS

We identified seven randomised trials in which 5583 patients were randomly assigned to Absorb BVS (n=3261) or metallic EES (n=2322) and followed up for 2 years. BVS had higher 2-year relative risks of the device-oriented composite endpoint than did EES (9·4% [304 of 3217] vs 7·4% [169 of 2299]; relative risk [RR] 1·29 [95% CI 1·08-1·56], p=0·0059). These differences were driven by increased rates of target vessel-related myocardial infarction (5·8% [187 of 3218] vs 3·2% [74 of 2299]; RR 1·68 [95% CI 1·29-2·19], p=0·0003) and ischaemia-driven target lesion revascularisation (5·3% [169 of 3217] vs 3·9% [90 of 2300]; 1·40 [1·09-1·80], p=0·0090) with BVS, with non-significant differences in cardiac mortality. The cumulative 2-year incidence of device thrombosis was higher with BVS than with EES (2·3% [73 of 3187] vs 0·7% [16 of 2281]; RR 3·35 [95% CI 1·96-5·72], p<0·0001). Landmark analysis between 1 and 2 years also showed higher rates of the device-oriented composite endpoint (3·3% [69 of 2100] vs 1·9% [23 of 1193]; RR 1·64 [95% CI 1·03-2·61], p=0·0376) and device thrombosis (0·5% [11 of 2085] vs none [0 of 1183], p<0·0001) in BVS-treated patients than in EES-treated patients.

INTERPRETATION

BVS was associated with increased rates of composite device-oriented adverse events and device thrombosis cumulatively at 2 years and between 1 and 2 years of follow-up compared with EES.

FUNDING

Abbott Vascular.

Comparative Biomechanical Behavior and Healing Profile of a Novel Thinned Wall Ultrahigh Molecular Weight Amorphous Poly-l-Lactic Acid Sirolimus-Eluting Bioresorbable Coronary Scaffold

BACKGROUND

Mechanical strength of bioresorbable scaffolds (BRS) is highly dependent on strut dimensions and polymer features. To date, the successful development of thin-walled BRS has been challenging. We compared the biomechanical behavior and vascular healing profile of a novel thin-walled (115 µm) sirolimus-eluting ultrahigh molecular weight amorphous poly-l-lactic acid-based BRS (APTITUDE, Amaranth Medical [AMA]) to Absorb (bioresorbable vascular scaffold [BVS]) using different experimental models.

METHODS AND RESULTS

In vitro biomechanical testing showed no fractures in the AMA-BRS when overexpanded 1.3 mm above nominal dilatation values (≈48%) and lower number of fractures on accelerated cycle testing over time (at 21 K cycles=20.0 [19.5-20.5] in BVS versus 4.0 [3.0-4.3] in AMA-BRS). In the healing response study, 35 AMA-BRS and 23 BVS were implanted in 58 coronary arteries of 23 swine and followed-up to 180 days. Scaffold strut healing was evaluated in vivo using weekly optical coherence tomography analysis. At 14 days, the AMA-BRS demonstrated a higher percentage of embedded struts (71.0% [47.6, 89.1] compared with BVS 40.3% [20.5, 63.2]; P=0.01). At 21 days, uncovered struts were still present in the BVS group (3.8% [2.1, 10.2]). Histopathology revealed lower area stenosis (AMA-BRS, 21.0±6.1% versus BVS 31.0±4.5%; P=0.002) in the AMA-BRS at 28 days. Neointimal thickness and inflammatory scores were comparable between both devices at 180 days.

CONCLUSIONS

A new generation thinned wall BRS displayed a more favorable biomechanical behavior and strut healing profile compared with BVS in normal porcine coronary arteries. This novel BRS concept has the potential to improve the clinical outcomes of current generation BRS.

Bioresorbable Vascular Scaffolds for Coronary Revascularization

Contemporary metallic drug-eluting stents are associated with very good 1-year outcomes but an ongoing risk of stent-related adverse events (thrombosis, myocardial infarction, restenosis) after 1 year. The pathogenesis of these very late events is likely related to the permanent presence of the metal stent frame or polymer. Bioresorbable scaffolds have been developed to provide drug delivery and mechanical support functions similar to metallic drug-eluting stents, followed by complete resorption with recovery of more normal vascular structure and function, potentially improving very late clinical outcomes. A first-generation bioresorbable scaffold has been demonstrated to be noninferior to a contemporary metallic drug-eluting stents for overall 1-year patient-oriented and device-oriented outcomes. Increased rates of scaffold thrombosis and target vessel-related myocardial infarction were noted that may be mitigated by improved patient and lesion selection, procedural technique, and device iteration. Large-scale, randomized, clinical trials are ongoing to determine the long-term relative efficacy and safety of bioresorbable scaffolds compared with current metallic drug-eluting stents.