Bioresorption and Vessel Wall Integration of a Fully Bioresorbable Polymeric Everolimus-Eluting Scaffold

Coronary bioresorbable metallic stents: Advancements and future perspectives

Percutaneous coronary intervention is a critical treatment for coronary artery disease, particularly myocardial infarction, and is highly recommended in clinical guidelines. Traditional metallic stents, although initially effective, remain permanently in the artery and can lead to complications such as in-stent restenosis, late thrombosis, and chronic inflammation. Given the temporary need for stenting and the potential for late complications, bioresorbable stents have emerged as a promising alternative. However, bioresorbable polymeric stents have encountered significant clinical challenges due to their low mechanical strength and ductility, which increase the risks of thrombosis and local inflammation. Consequently, bioresorbable metals are being considered as a superior option for coronary stents. This review examines the progress of bioresorbable metallic stents from both preclinical and clinical perspectives, aiming to provide a theoretical foundation for future research. Iron, zinc, and magnesium are the primary materials used for these stents. Zinc-based bioresorbable stents have shown promise in preclinical studies due to their biocompatibility and vascular protective properties, although human clinical studies are still limited. Magnesium-based stents have demonstrated positive clinical outcomes, being fully absorbed within 12 months and showing low rates of late lumen loss and target lesion failure at 6- and 12-months post-implantation. Initial trials of iron-based stents have indicated favorable mid-term safety and efficacy, with complete absorption by the body within three years and consistent luminal expansion beyond six months post-implantation. Despite these advancements, further trials are needed for comprehensive validation. In conclusion, while current materials do not fully meet the ideal requirements, ongoing research should focus on developing bioresorbable stents with enhanced performance characteristics to better meet clinical needs.

Safety and efficacy of everolimus-eluting bioresorbable vascular scaffold for cardiac allograft vasculopathy (CART)

BACKGROUND

Cardiac allograft vasculopathy (CAV) is still the main drawback of heart transplantation (HTx) and percutaneous coronary intervention (PCI) is a palliative measure because of the high incidence of failure.

OBJECTIVE

This study aimed to investigate the safety and efficacy of bioresorbable scaffolds (BRSs) as potential novel therapeutic tool for the treatment of coronary stenoses in CAV.

METHODS

This is a multicenter, single-arm, prospective, open-label study (CART, NCT02377648), that included patients affected by advanced CAV treated with PCI and second-generation ABSORB BRS (Abbott Vascular). The primary endpoint was the incidence of 12-month angiographic in-segment scaffold restenosis (ISSR). Secondary endpoints were the incidence of major adverse cardiac events (MACEs) at 12- and 36-month follow-up and the incidence of ISSR at 36 months. A paired intracoronary imaging analysis at baseline and follow-up was also performed.

RESULTS

Between 2015 and 2017 35 HTx patients were enrolled and treated for 44 coronary lesions with 51 BRSs. The primary endpoint occurred in 13.5% of the lesions (5/37), with a cumulative ISSR rate up to 3 years of 16.2% (6/37). Angiographic lumen loss was 0.40 ± 0.62 mm at 12 months and 0.53 ± 0.57 mm at 36 months. Overall survival rate was 91.4% and 74.3%, and MACEs incidence 14.2% and 31.4% at 12 and 36 months, respectively. At the paired intracoronary imaging analysis, a significant increase of the vessel external elastic membrane area in the treated segment and some progression of CAV proximally to the BRS were detected.

CONCLUSIONS

BRS-based PCI for the treatment of CAV is feasible and safe, with an ISSR incidence similar to what reported in retrospective studies with drug-eluting stents.

The Absorb GT1 Bioresorbable Vascular Scaffold System - 5-Year Post-Market Surveillance Study in Japan

BACKGROUND

The 1-year clinical outcomes of the Absorb GT1 Japan post-market surveillance (PMS) suggested that an appropriate intracoronary imaging-guided bioresorbable vascular scaffold (BVS) implantation technique may reduce the risk of target lesion failure (TLF) and scaffold thrombosis (ST) associated with the Absorb GT1 BVS. The long-term outcomes through 5 years are now available.

METHODS AND RESULTS

This study enrolled 135 consecutive patients (n=139 lesions) with ischemic heart disease in whom percutaneous coronary intervention (PCI) with the Absorb GT1 BVS was attempted. Adequate lesion preparation, imaging-guided appropriate sizing, and high-pressure post-dilatation using a non-compliant balloon were strongly encouraged. All patients had at least 1 Absorb GT1 successfully implanted at the index procedure. Intracoronary imaging was performed in all patients (optical coherence tomography: 127/139 [91.4%] lesions) and adherence to the implantation technique recommendations was excellent: predilatation, 100% (139/139) lesions; post-dilatation, 98.6% (137/139) lesions; mean (±SD) post-dilatation pressure, 18.8±3.5 atm. At 5 years, the follow-up rate was 87.4% (118/135). No definite/probable ST was reported through 5 years. The cumulative TLF rate was 5.1% (6/118), including 2 cardiac deaths, 1 target vessel-attributable myocardial infarction, and 3 ischemia-driven target lesion revascularizations.

CONCLUSIONS

Appropriate intracoronary imaging-guided BVS implantation, including the proactive use of pre- and post-balloon dilatation during implantation may be beneficial, reducing the risk of TLF and ST through 5 years.

Long-term intracoronary imaging and physiological measurements of bioresorbable scaffolds and untreated atherosclerotic plaques

BACKGROUND

Bioresorbable scaffolds (BRS) provide the prospect of restoring the anatomic and physiologic characteristics of the vascular wall.

OBJECTIVE

This study sought to examine the long-term outcomes of BRS-based coronary intervention in a young population with diffuse and severe coronary atherosclerotic disease (CAD) and to compare the long-term evolution of treated segments versus the natural progression of untreated non-flow limiting stenoses.

METHODS

Observational, single-center cohort study that prospectively included patients that underwent percutaneous coronary intervention with implantation of ABSORB BRS (Abbott Vascular). The clinical endpoint was the incidence of device-oriented composite endpoint (DoCE) up to 5 years follow-up. A subgroup of patients with baseline intracoronary imaging assessment of long lesions and/or multivessel disease underwent elective angiographic (70 patients, 129 lesions) and intracoronary imaging (55 patients, 102 lesions) follow-up. Paired intravascular ultrasound (IVUS) and quantitative flow reserve (QFR) were analyzed.

RESULTS

Between 2012 and 2017, 159 patients (mean age 54.0 ± 11.1) with native CAD were treated with BRS on 247 lesions. Patients were mainly at their first cardiac event, mostly acute coronary syndromes (86.5%). At the median follow-up time of 56 months [41-65], DoCE occurred in 15/159 (9.4%) patients, while non-target vessel-oriented composite endpoint occurred in 16 patients (10.4%). A significant atherosclerotic progression was detected on residual non-flow limiting plaques as per IVUS and QFR assessment, while no significant change was detected in the treated segment.

CONCLUSIONS

Mild-to-moderate asymptomatic CAD progressed significantly at 5-year despite OMT. BRS-treated segments had a less aggressive progression at 5-year despite more severe and symptomatic CAD at baseline.

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

Aims

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

Methods

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

Results

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

Conclusion

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

In vivo degradation and endothelialization of an iron bioresorbable scaffold

Detection of in vivo biodegradation is critical for development of next-generation medical devices such as bioresorbable stents or scaffolds (BRSs). In particular, it is urgent to establish a nondestructive approach to examine in vivo degradation of a new-generation coronary stent for interventional treatment based on mammal experiments; otherwise it is not available to semi-quantitatively monitor biodegradation in any clinical trial. Herein, we put forward a semi-quantitative approach to measure degradation of a sirolimus-eluting iron bioresorbable scaffold (IBS) based on optical coherence tomography (OCT) images; this approach was confirmed to be consistent with the present weight-loss measurements, which is, however, a destructive approach. The IBS was fabricated by a metal-polymer composite technique with a polylactide coating on an iron stent. The efficacy as a coronary stent of this new bioresorbable scaffold was compared with that of a permanent metal stent with the name of trade mark Xience, which has been widely used in clinic. The endothelial coverage on IBS was found to be greater than on Xience after implantation in a rabbit model; and our well-designed ultrathin stent exhibited less individual variation. We further examined degradation of the IBSs in both minipig coronary artery and rabbit abdominal aorta models. The present result indicated much faster iron degradation of IBS in the rabbit model than in the porcine model. The semi-quantitative approach to detect biodegradation of IBS and the finding of the species difference might be stimulating for fundamental investigation of biodegradable implants and clinical translation of the next-generation coronary stents.

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A semi-quantitative OCT method was suggested to evaluate in vivo biodegradation of an iron based coronary stent IBS in a nondestructive manner.

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The in vivo biodegradation of IBS exhibited dependence on animal species.

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The endothelial coverage on the biodegradable stent IBS was better than on the commercialized nonbiodegradable stent Xience in rabbits.

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.

Preclinical comparative assessment of a dedicated pediatric poly-L-lactic-acid-based bioresorbable scaffold with a low-profile bare metal stent

BACKGROUND

Polymer-based bioresorbable scaffolds (PBBS) have been assessed for coronary revascularization with mixed outcomes. Few studies have targeted pediatric-specific scaffolds. We sought to assess safety, efficacy, and short-term performance of a dedicated drug-free PBBS pediatric scaffold compared to a standard low-profile bare metal stent (BMS) in central and peripheral arteries of weaned piglets.

METHODS

Forty-two devices (22 Elixir poly-L-lactic-acid-based pediatric bioresorbable scaffolds [BRS] [6 × 18 mm] and 20 control BMS Cook Formula 418 [6 × 20 mm]) were implanted in the descending aorta and pulmonary arteries (PAs) of 14 female Yucatan piglets. Quantitative measurements were collected on the day of device deployment and 30 and 90 days postimplantation to compare device patency and integrity.

RESULTS

The BRS has a comparable safety profile to the BMS in the acute setting. Late lumen loss (LLL) and percent diameter stenosis (%DS) were not significantly different between BRS and BMS in the PA at 30 days. LLL and %DS were greater for BRS versus BMS in the aorta at 30 days postimplantation (LLL difference: 0.96 ± 0.26; %DS difference: 16.15 ± 4.51; p < .05). At 90 days, %DS in the aortic BRS was less, and PA BRS LLL was also less than BMS. Histomorphometric data showed greater intimal proliferation and area stenosis in the BRS at all time points and in all vessels.

CONCLUSIONS

A dedicated PBBS pediatric BRS has a favorable safety profile in the acute/subacute setting and demonstrates characteristics that are consistent with adult BRSs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

Little is known about serial changes in lumen and device dimensions after bioresorbable scaffold implantation in a growing animal model.

METHODS AND RESULTS

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

CONCLUSIONS

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

Balloons and Stents and Scaffolds: Preclinical Evaluation of Interventional Devices for Occlusive Arterial Disease

Atherosclerosis places a significant burden on humankind; it is the leading cause of mortality globally, and for those living with atherosclerosis, it can significantly impact quality of life. Fortunately, treatment advances have effectively reduced the morbidity and mortality related to atherosclerosis, with one such modality being percutaneous intervention (PCI) to open occluded arteries. Over the 40-year history of PCI, preclinical models have played a critical role in demonstrating proof of concept, characterizing the in vivo behavior (pharmacokinetics, degradation) and providing a reasonable assurance of biologic safety of interventional devices before entering into clinical trials. Further, preclinical models may provide insight into the potential efficacy of these devices with the appropriate study design and end points. While several species have been used in the evaluation of interventional devices, the porcine model has been the principal model used in the evaluation of safety of devices for both coronary and endovascular treatments. This article reviews the fundamentals of permanent stents, transient scaffolds, and drug-coated balloons and the models, objectives, and methods used in their preclinical evaluation.

Three-Year Results of the Absorb Everolimus-Eluting Bioresorbable Vascular Scaffold in Infrapopliteal Arteries

PURPOSE

To investigate the midterm performance of the everolimus-eluting Absorb bioresorbable vascular scaffold (BVS) for the treatment of symptomatic infrapopliteal atherosclerotic disease.

METHODS

A single-center study prospectively enrolled 48 symptomatic patients (mean age 82.1±8.0 years; 27 men) between September 2013 and February 2018 to evaluate the Absorb everolimus-eluting BVS system in distal popliteal and tibial lesions. Mean lesion length was 20.1±10.8 mm. Following predilation, up to 2 BVS were implanted in target lesions in 55 limbs. Clinical and duplex ultrasound follow-up was performed at 1, 3, 6, 12, 24, 36, and 48 months to determine 30-day morbidity and midterm Kaplan-Meier estimates of binary restenosis, clinically-driven target lesion revascularization (CD-TLR), amputation, and mortality.

RESULTS

Seventy-one scaffolds were implanted to treat 61 lesions. Technical success was achieved in all patients, with no amputation, death, or target limb bypass surgery within 30 days of the index procedure. There was 1 early thrombotic occlusion of 2 BVS in a previously anticoagulated patient not given antiplatelet medication after the procedure. During a mean follow-up of 24.0±15.3 months, 11 (23%) patients died; the remaining 37 were available for follow-up. Binary restenosis (50%-75%) was detected in 6 (8%) scaffolds. Primary patency estimates at 12, 24, and 36 months were 92.2%, 90.3%, and 81.1%; freedom from CD-TLR estimates were 97.2%, 97.2%, and 87.3% at the same time points. No late scaffold thrombosis has been observed. The majority of the 55 limbs (51, 93%) were clinically improved; 4 (7%) were unchanged. Thirty-six (92%) of 39 limbs treated for tissue loss achieved complete wound healing, with no major amputation (limb salvage 100%).

CONCLUSION

Midterm follow-up demonstrates excellent safety, patency, and freedom from CD-TLR rates using the Absorb bioresorbable vascular scaffold below the knee.

Multianalysis with optical coherence tomography and vasomotion in everolimus-eluting stents and everolimus-eluting biovascular scaffolds: the MOVES trial

Aims

To compare endothelium-dependent vasomotor function and vascular healing 15 months after implantation of two new-generation drug-eluting stents and biovascular scaffolds (BVS).

Methods and results

A total of 28 patients previously treated with a SYNERGY stent (bioabsorbable polymer everolimus-eluting stents (BP-EES)), a PROMUS stent (persistent polymer everolimus-eluting stents (PP-EES)) or an ABSORB (BVS) underwent control coronary angiography, 15 months after implantation, coupled with optical coherence tomography imaging and supine bicycle exercise. Intracoronary nitroglycerin was administered after exercise testing. Coronary vasomotor response was assessed using quantitative coronary angiography at rest, during supine bicycle exercise and after nitroglycerin. The primary end point was the percent change in mean lumen diameter compared with baseline. Secondary end points were strut coverage and apposition.There were no significant differences in vasomotor response between the three treatment groups. Patients with PP-EES showed significant vasoconstriction of the proximal peristent segment at maximum exercise (P=0.02). BP-EES (2.7%, 95% CI 0 to 5.5) and BVS (3.2%, 95% CI 0 to 6.7) showed less uncovered struts than PP-EES (12.1%, 95% CI 2.9 to 21.3, P=0.02 and 0.09, respectively). Complete strut apposition was more frequently seen with BP-EES (99.6%, 95% CI 99.2 to 100) than with BVS (98.9%, 95% CI 98.2 to 99.6, P=0.04) or PP-EES (95.0%, 95% CI 91.6 to 98.5, P=0.001).

Conclusion

BVS and thin strut BP-EES have a reassuring vasomotion profile, suggesting minimal endothelial dysfunction 15 months after implantation.

Tissue characterization with depth-resolved attenuation coefficient and backscatter term in intravascular optical coherence tomography images

An important application of intravascular optical coherence tomography (IVOCT) for atherosclerotic tissue analysis is using it to estimate attenuation and backscatter coefficients. This work aims at exploring the potential of the attenuation coefficient, a proposed backscatter term, and image intensities in distinguishing different atherosclerotic tissue types with a robust implementation of depth-resolved (DR) approach. Therefore, the DR model is introduced to estimate the attenuation coefficient and further extended to estimate the backscatter-related term in IVOCT images, such that values can be estimated per pixel without predefining any delineation for the estimation. In order to exclude noisy regions with a weak signal, an automated algorithm is implemented to determine the cut-off border in IVOCT images. The attenuation coefficient, backscatter term, and the image intensity are further analyzed in regions of interest, which have been delineated referring to their pathology counterparts. Local statistical values were reported and their distributions were further compared with a two-sample t-test to evaluate the potential for distinguishing six types of tissues. Results show that the IVOCT intensity, DR attenuation coefficient, and backscatter term extracted with the reported implementation are complementary to each other on characterizing six tissue types: mixed, calcification, fibrous, lipid-rich, macrophages, and necrotic core.

Arterial Remodeling After Bioresorbable Scaffolds and Metallic Stents

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Paving the way to a bioresorbable technology: Development of the absorb BRS program

Bioresorbable scaffolds (BRS) combine attributes of the preceding generations of percutaneous coronary intervention (PCI) devices with new technologies to result in a novel therapy promoted as being the fourth generation of PCI. By providing mechanical support and drug elution to suppress restenosis, BRS initially function similarly to drug eluting stents. Thereafter, through their degradation, BRS undergo a decline in radial strength, allowing a gradual transition of mechanical function from the scaffold back to the artery in order to provide long term effectiveness similar to balloon angioplasty. The principles of operation of BRS, whether of polymeric or metallic composition, follow three phases of functionality reflective of differing physiological requirements over time: revascularization, restoration, and resorption. In this review, these three fundamental performance phases and the metrics for the nonclinical evaluation of BRS, including both bench and preclinical testing, are discussed. © 2016 Wiley Periodicals, Inc.

Analysis and compensation for the effect of the catheter position on image intensities in intravascular optical coherence tomography

Intravascular optical coherence tomography (IVOCT) is an imaging technique that is used to analyze the underlying cause of cardiovascular disease. Because a catheter is used during imaging, the intensities can be affected by the catheter position. This work aims to analyze the effect of the catheter position on IVOCT image intensities and to propose a compensation method to minimize this effect in order to improve the visualization and the automatic analysis of IVOCT images. The effect of catheter position is modeled with respect to the distance between the catheter and the arterial wall (distance-dependent factor) and the incident angle onto the arterial wall (angle-dependent factor). A light transmission model incorporating both factors is introduced. On the basis of this model, the interaction effect of both factors is estimated with a hierarchical multivariant linear regression model. Statistical analysis shows that IVOCT intensities are significantly affected by both factors with p<0.001, as either aspect increases the intensity decreases. This effect differs for different pullbacks. The regression results were used to compensate for this effect. Experiments show that the proposed compensation method can improve the performance of the automatic bioresorbable vascular scaffold strut detection.