Freeing the vessel from metallic cage: what can we achieve with bioresorbable vascular scaffolds? Cardiovasc Interv Ther. 2012;27:141-154. [PMID: 22569783 DOI: 10.1007/s12928-012-0101-8]

Comprehensive clinical outcomes of drug-coated balloon treatment for coronary artery disease. Insights from a single-center experience

BACKGROUND

Some clinical trials have verified the efficacy and safety of paclitaxel drug-coated balloon (DCB) for small vessel coronary artery disease. However, nonsmall vessel and calcified lesions received less attention.

AIMS

This study aimed to investigate the efficacy of DCB treatment for various types of coronary artery lesions, including not only small vessel disease but also nonsmall vessel disease and calcified lesions. In this real-world clinical practice study, in-stent restenosis was excluded.

METHODS

This study consecutively included 934 patients with 1751 nonstented lesions who received DCB at a cardiovascular center in Kyoto Katsura Hospital in Japan between 2009 and 2012 and 2014 to 2019. This study enrolled and retrospectively analyzed all of the patients. Eligible patients routinely underwent follow-up angiography at 6-8 months after percutaneous coronary intervention. The primary endpoint includes target lesion revascularization (TLR) during follow-up. Further, this study calculated the predictor of TLR using multivariate analysis.

RESULTS

This study included the lesions involving 46.4% of type B2/C, 26.9% with severe calcification, and 6.0% with DCB restenosis. Mean DCB diameter and length were 2.75 ± 0.51 mm and 24.2 ± 9.6 mm, respectively. The median follow-up duration was 18 months. Follow-up angiography revealed a TLR rate of 9% and a restenosis rate of 9%. This study identified hemodialysis and current smoking as independent TLR predictors.

CONCLUSION

In routine clinical practice, the effectiveness of DCB was observed consistently across various types of coronary artery disease.

Corroded iron stent increases fibrin deposition and promotes endothelialization after stenting

Poststent restenosis is caused by insufficient endothelialization and is one of the most serious clinical complications of stenting. We observed a rapid endothelialization rate and increased fibrin deposition on the surfaces of the corroded iron stents. Thus, we hypothesized that corroded iron stents would promote endothelialization by increasing fibrin deposition on rough surfaces. To verify this hypothesis, we conducted an arteriovenous shunt experiment to analyze fibrin deposition in the corroded iron stents. We implanted a corroded iron stent in both the carotid and iliac artery bifurcations to elucidate the effects of fibrin deposition on endothelialization. Co-culture experiments were conducted under dynamic flow conditions to explore the relationship between fibrin deposition and rapid endothelialization. Our findings indicate that, from the generation of corrosion pits, the surface of the corroded iron stent was rough, and numerous fibrils were deposited in the corroded iron stent. Fibrin deposition in corroded iron stents facilitates endothelial cell adhesion and proliferation, which, in turn, promotes endothelialization after stenting. Our study is the first to elucidate the role of iron stent corrosion in endothelialization, pointing to a new direction for preventing clinical complications caused by insufficient endothelialization.

Clinical expert consensus document on drug-coated balloon for coronary artery disease from the Japanese Association of Cardiovascular Intervention and Therapeutics

Drug-coated balloon (DCB) technology was developed to deliver the antiproliferative drugs to the vessel wall without leaving any permanent prosthesis or durable polymers. The absence of foreign material can reduce the risk of very late stent failure, improve the ability to perform bypass-graft surgery, and reduce the need for long-term dual antiplatelet therapy, potentially reducing associated bleeding complications. The DCB technology, like the bioresorbable scaffolds, is expected to be a therapeutic approach that facilitates the "leave nothing behind" strategy. Although newer generation drug-eluting stents are the most common therapeutic strategy in modern percutaneous coronary interventions, the use of DCB is steadily increasing in Japan. Currently, the DCB is only indicated for treatment of in-stent restenosis or small vessel lesions (< 3.0 mm), but potential expansion for larger vessels (≥ 3.0 mm) may hasten its use in a wider range of lesions or patients with obstructive coronary artery disease. The task force of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) was convened to describe the expert consensus on DCBs. This document aims to summarize its concept, current clinical evidence, possible indications, technical considerations, and future perspectives.

Degradation behaviors and in-vivo biocompatibility of a rare earth- and aluminum-free magnesium-based stent

Biodegradable stents can provide scaffolding and anti-restenosis benefits in the short term and then gradually disappear over time to free the vessel, among which the Mg-based biodegradable metal stents have been prosperously developed. In the present study, a Mg-8.5Li (wt.%) alloy (RE- and Al-free) with high ductility (> 40%) was processed into mini-tubes, and further fabricated into finished stent through laser cutting and electropolishing. In-vitro degradation test was performed to evaluate the durability of this stent before and after balloon dilation. The influence of plastic deformation and residual stress (derived from the dilation process) on the degradation was checked with the assistance of finite element analysis. In addition, in-vivo degradation behaviors and biocompatibility of the stent were evaluated by performing implantation in iliac artery of minipigs. The balloon dilation process did not lead to deteriorated degradation, and this stent exhibited a decent degradation rate (0.15 mm/y) in vitro, but divergent result (> 0.6 mm/y) was found in vivo. The stent was almost completely degraded in 3 months, revealing an insufficient scaffolding time. Meanwhile, it did not induce possible thrombus, and it was tolerable by surrounding tissues in pigs. Besides, endothelial coverage in 1 month was achieved even under the severe degradation condition. In the end, the feasibility of this stent for treatment of benign vascular stenosis was generally discussed, and perspectives on future improvement of Mg-Li-based stents were proposed.

Non-Oncologic Applications of Nanomedicine-Based Phototherapy

Phototherapy is widely applied to various human diseases. Nanomedicine-based phototherapy can be classified into photodynamic therapy (PDT) and photothermal therapy (PTT). Activated photosensitizer kills the target cells by generating radicals or reactive oxygen species in PDT while generating heat in PTT. Both PDT and PTT have been employed for treating various diseases, from preclinical to randomized controlled clinical trials. However, there are still hurdles to overcome before entering clinical practice. This review provides an overview of nanomedicine-based phototherapy, especially in non-oncologic diseases. Multiple clinical trials were undertaken to prove the therapeutic efficacy of PDT in dermatologic, ophthalmologic, cardiovascular, and dental diseases. Preclinical studies showed the feasibility of PDT in neurologic, gastrointestinal, respiratory, and musculoskeletal diseases. A few clinical studies of PTT were tried in atherosclerosis and dry eye syndrome. Although most studies have shown promising results, there have been limitations in specificity, targeting efficiency, and tissue penetration using phototherapy. Recently, nanomaterials have shown promising results to overcome these limitations. With advanced technology, nanomedicine-based phototherapy holds great potential for broader clinical practice.

Preclinical investigation of neoatherosclerosis in magnesium-based bioresorbable scaffolds versus thick-strut drug-eluting stents

AIMS

Neoatherosclerosis is a frequent finding after implantation of permanent metallic stents. Bioresorbable scaffolds (BRS) are considered to reduce the incidence of neoatherosclerosis owing to their dissolution and consequent vascular restoration. The aim of this study was to evaluate the formation of neoatherosclerosis between magnesium-based BRS and thick-strut metallic drug-eluting stents (DES) in a rabbit model of neoatherosclerosis and in proportion to the effect of high-dose statin medication.

METHODS AND RESULTS

Fully bioresorbable magnesium scaffolds (BRS, n=45) and thick-strut permanent metallic DES of equivalent geometry and design (n=45) were implanted into the iliac arteries of New Zealand White rabbits (n=45) following endothelial balloon injury and exposure to a cholesterol diet. Endothelialisation was assessed in 12 animals after 35 days using scanning electron microscopy (SEM), showing significantly enhanced re-endothelialisation above struts in the BRS (n=13) compared to DES (n=10). Eleven (11) animals were terminated for baseline assessment after 91 days while the remaining 22 animals were randomised to receive high-dose statin treatment (3 mg/kg) or placebo. BRS-treated vessels showed a significant reduction in foam cell infiltration as a sign of early neoatherosclerosis by histology and OCT when compared to thick-strut DES-treated vessels. Statin treatment resulted in significant reduction of foam cell infiltration in BRS and DES by histology.

CONCLUSIONS

Our findings suggest reduced neoatherosclerosis formation in magnesium-based BRS relative to thick-strut DES. High-dose statin treatment may be a promising measure to reduce neoatherosclerosis progression, both on its own and in synergy with site-targeted device-based treatment.

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

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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.

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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.

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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.

Undiscovered pathology of transient scaffolding t1remains a driver of failures in clinical trials

AIM

To statistically examine the released clinical trials and meta-analyses of polymeric bioresorbable scaffolds resuming the main accomplishments in the field with a translation to the routine clinical practice.

METHODS

The statistical power in clinical trials such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA, and few meta-analyses by the post hoc odds ratio-based sample size calculation, and the patterns of artery remodeling published in papers from ABSORB A and B trials were evaluated.

RESULTS

The phenomenal admiration from the first ABSORB studies in 2006-2013 was replaced by the tremendous disappointment in 2014-2017 due to reported relatively higher rates of target lesion failure (a mean prevalence of 9.16%) and device thrombosis (2.38%) in randomized controlled trials. Otherwise, bioresorbable vascular scaffold (BVS) performs as well as the metallic drug-eluting stent (DES) with a trend toward some benefits for cardiac mortality [risk ratio (RR), 0.58-0.94, P > 0.05]. The underpowered design was confirmed for some studies such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA trials, and meta-analyses of Polimeni, Collet, and Mahmoud with some unintentional bias (judged by the asymmetrical Funnel plot). Scaffold thrombosis rates with Absorb BRS were comparable with DES performed with a so-called strategy of the BVS implantation with optimized pre-dilation (P), sizing (S) and post-dilation (P) (PSP) implantation (RR, PSP vs no PSP 0.37) achieving 0.35 per 100 patient-years, which is comparable to the RR 0.49 with bare-metal stents and the RR 1.06 with everolimus DES. Both ABSORB II and ABSORB III trials were powered enough for a five-year follow-up, but the results were not entirely conclusive due to the mostly non-significant fashion of data. The powered meta-analyses were built mostly on statistically poor findings.

CONCLUSION

The misunderstanding of the pathology of transient scaffolding drives the failures of the clinical trials. More bench studies of the vascular response are required. Several next-generation BVS including multifunctional electronic scaffold grant cardiology with a huge promise to make BVS technology great again.

Plasmonic photothermal therapy of atherosclerosis with nanoparticles: long-term outcomes and safety in NANOM-FIM trial

AIM

The safety options in nanomedicine raise an issue of the optimal niche at the real-world clinical practice.

METHODS

This is an observational prospective cohort analysis of the 5-year clinical outcomes at the intention-to-treat population (nano vs ferro vs stenting; n = 180) of NANOM first-in-man trial (NCT01270139).

RESULTS

Mortality (6 vs 9 vs 10 cases of cardiac death in groups, p < 0.05), major adverse cardiovascular events (14.3 vs 20.9 vs 22.9%, p = 0.04), late thrombosis (2 vs 4 vs 6, p < 0.05) and target lesion revascularization (3.8 vs 4.8 vs 5.7%, p = 0.04) were significantly higher in ferro group and stent control at 60 months.

CONCLUSION

NANOM first-in-man trial demonstrates high safety with better rate of mortality, major adverse cardiovascular events and target lesion revascularization at the long-term follow-up if compare with stent XIENCE V.

Clinical Outcomes of Bioresorbable Scaffold in Coronary Artery Disease: A Systematic Literature Review

OBJECTIVES

We aim to perform a systematic literature review on all studies reporting the clinical outcomes of the use of bioresorbable scaffolds (BRS) in different settings of coronary artery disease (CAD).

BACKGROUND

BRS are designed to provide early support of the vessel wall postangioplasty, deliver antiproliferative agents to prevent excessive hyperplastic healing responses and finally "disappear" when no longer required. Emerging data have provided evidence of their use in specific clinical scenarios.

METHODS

A comprehensive literature search was performed by 2 independent reviewers utilizing MEDLINE, EMBASE, and Cochrane Library databases. The only 2 CE marked BRS: everolimus-eluting Bioresorbable vascular scaffold ABSORB BVS and the myolimus-eluting DESolve Bioresorbable Coronary Scaffold (BCS) System were included.

RESULTS

The studies were categorized into: ST elevation myocardial infarction (STEMI), stable CAD, and "all-comers" group. Thirty-one studies were included; 8 in STEMI patients (all ABSORB), 15 in stable CAD patients. In the STEMI group (n = 606), acute procedural success ranged from 96% to 100%, cardiac mortality 0-9.1%, recurrent MI and stent thrombosis rates were 0-4.3%. In the stable CAD group, the 13 ABSORB studies (n = 3259) demonstrated cardiac mortality rate of 0-0.6%, recurrent MI rate 0-4.5%, and stent thrombosis rate 0-4.3%

CONCLUSIONS

Current clinical data suggest the BRS, especially the ABSORB BVS, may represent a reasonable alternative to DES in uncomplicated coronary anatomy.

Bioresorbable Scaffolds for Atheroregression: Understanding of Transient Scaffolding

This review focuses on the clinical and biological features of the bioresorbable scaffolds in interventional cardiology highlighting scientific achievements and challenges of the transient scaffolding with Absorb BVS. Special attention is granted to the vascular biology pathways which, involved in the resorption of scaffold, artery remodeling and mechanisms of Glagovian atheroregression setting the stage for subsequent clinical applications. Twenty five years ago Glagov described the phenomenon of limited external elastic membrane enlargement in response to an increase in plaque burden. We believe this threshold becomes the target for development of strategies that reverse atherosclerosis, and particularly transient scaffolding has a potential to be a tool to ultimately conquer atherosclerosis.

Silica-gold nanoparticles for atheroprotective management of plaques: results of the NANOM-FIM trial

BACKGROUND

Atheroregression becomes an attractive target for cardiovascular treatment. Some clinical trials have demonstrated that intensive therapy with rosuvastatin or recombinant ApoA-I Milano can partially reduce the total atheroma volume (TAV) up to 6.38 mm(3) or 14.1 mm(3) respectively. Our previous bench studies of selected nanotechnologies documented TAV reduction up to an unprecedented 79.4 mm(3).

METHODS

The completed observational three arms (n = 180) first-in-man trial (the NANOM FIM trial) assessed (NCT01270139) the safety and feasibility of two delivery techniques for nanoparticles (NP), and plasmonic photothermal therapy (PPTT). Patients were assigned to receive either (1) nano-intervention with delivery of silica-gold NP in a bioengineered on-artery patch (n = 60), or (2) nano-intervention with delivery of silica-gold iron-bearing NP with targeted micro-bubbles and stem cells using a magnetic navigation system (n = 60) versus (3) stent implantation (n = 60). The primary outcome was TAV at 12 months.

RESULTS

The mean TAV reduction at 12 months in the Nano group was 60.3 mm(3) (SD 39.5; min 41.9 mm(3), max 94.2 mm(3); p < 0.05) up to mean 37.8% (95% CI: 31.1%, 51.7%; p < 0.05) plaque burden. The analysis of the event free survival of the ongoing clinical follow-up shows the significantly lower risk of cardiovascular death in the Nano group when compared with others (91.7% vs. 81.7% and 80% respectively; p < 0.05) with no cases of the target lesion-related complications.

CONCLUSIONS

PPTT using silica-gold NP associated with significant regression of coronary atherosclerosis.

Plasmonic photothermal therapy for atheroregression below Glagov threshold

The advent of nanomedicine allowed for the development and design of tools that enhance detailed diagnosis and target treatment of atherosclerosis. Given the rapid progress in nanoagent synthesis and utility, clinical application of these technologies can be anticipated in the near future. This review article focuses on the development of these technologies in interventional cardiology, with the main goal of achieving atheroregression below a Glagov threshold of 40%. Special attention is given to plasmonic photothermal therapy. Vascular remodeling maintains the lumen dimension as long as the external elastic membrane can accommodate an increase in plaque burden that does not surpass a certain threshold. We propose that this threshold becomes the target for the development of strategies that reverse atherosclerosis, especially for the generation of devices and tools of nanomedicine.