BIOSOLVE-IV-registry: Safety and performance of the Magmaris scaffold: 12-month outcomes of the first cohort of 1,075 patients

Optimal lesion preparation before implantation of a Magmaris bioresorbable scaffold in patients with coronary artery stenosis: Rationale, design and methodology of the OPTIMIS study

Introduction

Percutaneous coronary intervention with implantation of a bioresorbable scaffold (BRS) provide the vessel support for a limited period allowing the vessel to restore normal vasomotion after degradation of the BRS, opposed to treatment with drug-eluting stents where the metal persist in the vessel wall. Late lumen loss and reduction in lumen area after implantation have been reported. The purpose of this study was to investigate whether intense pre-dilatation before BRS implantation resulted in less reduction of minimal lumen area at 6- and 12-month follow-up after implantation of a Magmaris BRS (MgBRS). Coronary imaging with optical coherence tomography (OCT) and intravascular ultrasound (IVUS) was assessed to track changes in lumen and vessel dimensions.

Methods

The prospective Optimal lesion PreparaTion before Implantation of the Magmaris bioresorbable scaffold In patients with coronary artery Stenosis (OPTIMIS) study randomly assigned eighty-two patients with chronic coronary syndrome to two pre-dilatation treatment strategies. Patients were randomized in a 1:1 ratio to pre-dilatation with either a non-compliant scoring balloon or a standard non-compliant balloon prior to implantation of a MgBRS. The treated segment was evaluated with OCT and IVUS at baseline, after 6 and 12 months to assess changes in lumen and vessel dimensions. The hypothesis was that more intense pre-dilatation with a non-compliant scoring balloon before MgBRS implantation can reduce the risk of late lumen reduction compared to standard pre-dilatation. The power calculation used expected MLA after 6 months (6.22 mm2 for the scoring balloon and 5.01 mm2 for the standard non-compliant balloon), power of 80 %, significance level of 0.05 and expected drop-out rate of 15 %, requiring 82 patients to be enrolled.

Results

Eighty-two patients were included in the study. Enrollment was from December 2020 to September 2023.

Conclusion

The hypothesis was that more intense pre-dilatation with a non-compliant scoring balloon before MgBRS implantation can reduce the risk of late lumen reduction compared to standard pre-dilatation.

Development and Future Trends of Protective Strategies for Magnesium Alloy Vascular Stents

Magnesium alloy stents have been extensively studied in the field of biodegradable metal stents due to their exceptional biocompatibility, biodegradability and excellent biomechanical properties. Nevertheless, the specific in vivo service environment causes magnesium alloy stents to degrade rapidly and fail to provide sufficient support for a certain time. Compared to previous reviews, this paper focuses on presenting an overview of the development history, the key issues, mechanistic analysis, traditional protection strategies and new directions and protection strategies for magnesium alloy stents. Alloying, optimizing stent design and preparing coatings have improved the corrosion resistance of magnesium alloy stents. Based on the corrosion mechanism of magnesium alloy stents, as well as their deformation during use and environmental characteristics, we present some novel strategies aimed at reducing the degradation rate of magnesium alloys and enhancing the comprehensive performance of magnesium alloy stents. These strategies include adapting coatings for the deformation of the stents, preparing rapid endothelialization coatings to enhance the service environment of the stents, and constructing coatings with self-healing functions. It is hoped that this review can help readers understand the development of magnesium alloy cardiovascular stents and solve the problems related to magnesium alloy stents in clinical applications at the early implantation stage.

Resorbable magnesium metal membrane for sinus lift procedures: a case series

BACKGROUND

The purpose of this case series was to demonstrate the use of a magnesium membrane for repairing the perforated membrane in both direct and indirect approaches, as well as its application in instances where there has been a tear of the Schneiderian membrane.

CASE PRESENTATION

The case series included four individual cases, each demonstrating the application of a magnesium membrane followed by bone augmentation using a mixture of xenograft and allograft material in the sinus cavity. In the first three cases, rupture of Schneiderian membrane occurred as a result of tooth extraction, positioning of the dental implant, or as a complication during the procedure. In the fourth case, Schneiderian membrane was perforated as a result of the need to aspirate a polyp in the maxillary sinus. In case one, 10 mm of newly formed bone is visible four months after graft placement. Other cases showed between 15 and 20 mm of newly formed alveolar bone. No residual magnesium membrane was seen on clinical inspection. The vertical and horizontal augmentations proved stable and the dental implants were placed in the previously grafted sites.

CONCLUSION

Within the limitations of this case series, postoperative clinical examination, and panoramic and CBCT images demonstrated that resorbable magnesium membrane is a viable material for sinus lift and Schneiderian membrane repair. The case series showed successful healing and formation of new alveolar bone with separation of the oral cavity and maxillary sinus in four patients.

Comparison of acute versus stable coronary syndrome in patients treated with the Magmaris scaffold: Two-year results from the Magmaris Multicenter Italian Registry

BACKGROUND

The magnesium Magmaris scaffold is the latest resorbable technology with low thrombogenicity, short scaffolding time, and almost complete resorption at 12 months (95 %). As compared with stable coronary artery disease (SCAD), acute coronary syndrome (ACS) is associated with increased risk of adverse clinical outcome after percutaneous coronary intervention. We analyzed the data of the Magmaris Multicenter Italian Registry to compare clinical outcomes in SCAD versus ACS patients.

METHODS

We evaluated the 24-month rates of target lesion failure (TLF) and scaffold thrombosis (ST). Device implantation procedures were performed according to the manufacturer's recommendations (proper patient/lesion selection, pre-dilatation, proper scaffold sizing, and post-dilatation). Dual antiplatelet therapy was terminated after 12 months.

RESULTS

Data from 207 patients (145 SCAD and 62 ACS) were collected from July 2016 to June 2018. The 2-year follow-up compliance was 92.8 % (192 patients). At 2 years, TLF rates were 7.4 % in the SCAD group and 8.8 % in the ACS group (p = 0.7); ST rates were 0 % in the SCAD group and 1.8 % in the ACS group (p = 0.1).

CONCLUSION

The 2-year clinical results from the Magmaris Multicenter Italian Registry are favorable in terms of TLF and ST, indicating the safety and effectiveness of the Magmaris scaffold in both SCAD and ACS patients.

Safety and efficacy of new-generation coronary bioresorbable scaffolds

INTRODUCTION

The concept of bioresorbable scaffolds (BRS) was born with the aim to reduce the rate of late and very late cardiac events related to drug-eluting stents. However, first-generation BRS failed to prove their short-term safety and efficacy. Based on data derived from early investigations, new-generation BRS have been developed and tested in preliminary studies. The present review's focus was to summarize the mechanical characteristics of these new scaffolds and the clinical evidence of their safety and efficacy.

EVIDENCE ACQUISITION

This systematic review was performed following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). PUBMED, Google Scholar, and Biomed central databases were analyzed. Only papers published in English and in peer-reviewed journals were selected to summarize current evidence about new generation BRS, with CE mark approval. Overall, 23 studies were included.

EVIDENCE SYNTHESIS

Data obtained from selected studies assessing the safety and efficacy of new generation BRS are encouraging. This is thanks to the progressive development of scaffolds with a different backbone structure and struts thickness that guarantee higher radial strength, flexibility, and resistance to fracture. These characteristics led to low rates of major adverse cardiac events and device-oriented composite endpoint at follow-up.

CONCLUSIONS

New-generation BRS have a good safety profile in stable patients with simple lesions, supported by a meticulous implantation technique. The first studies were performed on a small population with short-term follow-up, therefore new randomized clinical trials and registries are needed to expand the preliminary findings.

A new resorbable magnesium scaffold for de novo coronary lesions (DREAMS 3): one-year results of the BIOMAG-I first-in-human study

BACKGROUND

The third-generation coronary sirolimus-eluting magnesium scaffold, DREAMS 3G, is a further development of the DREAMS 2G (commercial name Magmaris), aiming to provide performance outcomes similar to drug-eluting stents (DES).

AIMS

The BIOMAG-I study aims to assess the safety and performance of this new-generation scaffold.

METHODS

This is a prospective, multicentre, first-in-human study with clinical and imaging follow-up scheduled at 6 and 12 months. The clinical follow-up will continue for 5 years.

RESULTS

A total of 116 patients with 117 lesions were enrolled. At 12 months, after completion of resorption, in-scaffold late lumen loss was 0.24±0.36 mm (median 0.19, interquartile range 0.06-0.36). The minimum lumen area was 4.95±2.24 mm² by intravascular ultrasound and 4.68±2.32 mm² by optical coherence tomography. Three target lesion failures were reported (2.6%, 95% confidence interval: 0.9-7.9), all clinically driven target lesion revascularisations. Cardiac death, target vessel myocardial infarction and definite or probable scaffold thrombosis were absent.

CONCLUSIONS

Data at the end of the resorption period of DREAMS 3G showed that the third-generation bioresorbable magnesium scaffold is clinically safe and effective, making it a possible alternative to DES.

CLINICALTRIALS

gov: NCT04157153.

Benchtop proof of concept and comparison of iron- and magnesium-based bioresorbable flow diverters

OBJECTIVE

Bioresorbable flow diverters (BRFDs) could significantly improve the performance of next-generation flow diverter technology. In the current work, magnesium and iron alloy BRFDs were prototyped and compared in terms of porosity/pore density, radial strength, flow diversion functionality, and resorption kinetics to offer insights into selecting the best available bioresorbable metal candidate for the BRFD application.

METHODS

BRFDs were constructed with braided wires made from alloys of magnesium (MgBRFD) or iron (FeBRFD). Pore density and crush resistance force were measured using established methods. BRFDs were deployed in silicone aneurysm models attached to flow loops to investigate flow diversion functionality and resorption kinetics in a simulated physiological environment.

RESULTS

The FeBRFD exhibited higher pore density (9.9 vs 4.3 pores/mm2) and crush resistance force (0.69 ± 0.05 vs 0.53 ± 0.05 N/cm, p = 0.0765, n = 3 per group) than the MgBRFD, although both crush resistances were within the range previously reported for FDA-approved flow diverters. The FeBRFD demonstrated greater flow diversion functionality than the MgBRFD, with significantly higher values of established flow diversion metrics (mean transit time 159.6 ± 11.9 vs 110.9 ± 1.6, p = 0.015; inverse washout slope 192.5 ± 9.0 vs 116.5 ± 1.5, p = 0.001; n = 3 per group; both metrics expressed as a percentage of the control condition). Last, the FeBRFD was able to maintain its braided structure for > 12 weeks, whereas the MgBRFD was almost completely resorbed after 5 weeks.

CONCLUSIONS

The results of this study demonstrated the ability to manufacture BRFDs with magnesium and iron alloys. The data suggest that the iron alloy is the superior material candidate for the BRFD application due to its higher mechanical strength and lower resorption rate relative to the magnesium alloy.

First-in-human evaluation of a novel ultrathin sirolimus-eluting iron bioresorbable scaffold: 3-year outcomes of the IBS-FIM trial

BACKGROUND

The first-generation polymeric bioresorbable scaffolds resulted in higher than acceptable 3-year rates of device-related adverse outcomes.

AIMS

We aimed to assess the intermediate-term safety and performance of a novel ultrathin-strut sirolimus-eluting iron bioresorbable scaffold (IBS) in non-complex coronary lesions.

METHODS

The prospective, single-arm, open-label IBS first-in-human study enrolled 45 patients, each with a single de novo lesion. Enrolled patients were randomly assigned to 2 follow-up cohorts. Angiographic and imaging follow-up with intravascular ultrasound and optical coherence tomography (OCT) were conducted at 6 and 24 months in cohort 1 (n=30) and at 12 and 36 months in cohort 2 (n=15). Clinical follow-up was conducted at 1, 6 and 12 months, and annually thereafter up to 5 years. The coprimary outcomes were target lesion failure (TLF) and angiographic late lumen loss (LLL) at 6 months.

RESULTS

A total of 45 patients were enrolled between April 2018 and January 2019. The mean age was 53.2 years, 77.8% were male, and 26.7% had diabetes. The TLF rates were 2.2% at 6 months and 6.7% at 3 years, which in all cases were due to clinically indicated target lesion revascularisation. No deaths, myocardial infarctions or stent thromboses occurred during 3-year follow-up. In-scaffold LLL was 0.33±0.27 mm at 6 months and 0.37±0.57 mm at 3 years. By OCT, the proportion of covered struts was 99.8% at 6 months and 100% after 1 year. The 3-year strut absorption rate was 95.4%.

CONCLUSIONS

In this first-in-human experience, an ultrathin IBS was safe and effective for the treatment of de novo non-complex coronary lesions up to 3-year follow-up.

Mid-term safe and effective profile of the Magmaris scaffold in percutaneous coronary intervention: a prospective, single-center study

Introduction

Significant advances have been made in the diagnosis and treatment of coronary artery disease over the years. New generations of scaffolds containing novel material and eluting drug have produced one of the most significant advancements in coronary intervention. The newest generation would be Magmaris with a magnesium frame and a sirolimus cover.

Methods

From July 2018 to August 2020, 58 patients treated with Magmaris at the University Medical Center Ho Chi Minh City were enrolled in this study.

Results

A total of 60 lesions were stented, 60.3% of which were left anterior descending (LAD) lesions. There was no in-hospital event. Within 1 year after discharge, we noted one myocardial infarction event that required target-lesion revascularization, one stroke event, one non-target-lesion revascularization patient, two target-vessel revascularization patients, and one in-stent thrombosis. Among them, one myocardial infarction occurrence, one non-target-lesion revascularization, and one in-stent thrombosis event were recorded within the first 30 days after discharge.

Conclusion

In conclusion, the Magmaris scaffold is a safe and effective option for structural procedures performed with imaging device support, particularly intravascular ultrasound.

Safety and performance of the third-generation drug-eluting resorbable coronary magnesium scaffold system in the treatment of subjects with de novo coronary artery lesions: 6-month results of the prospective, multicenter BIOMAG-I first-in-human study

Background

A third-generation coronary drug-eluting resorbable magnesium scaffold (DREAMS 3G) was developed to enhance the performance of previous scaffold generations and achieve angiographic outcomes comparable to those of contemporary drug-eluting stents.

Methods

This prospective, multicenter, non-randomized, first-in-human study was conducted at 14 centers in Europe. Eligible patients had stable or unstable angina, documented silent ischemia, or non-ST-elevation myocardial infarction, and a maximum of two single de novo lesions in two separate coronary arteries with a reference vessel diameter between 2.5 mm and 4.2 mm. Clinical follow-up was scheduled at one, six and 12 months and annually thereafter until five years. Invasive imaging assessments were scheduled six and 12 months postoperatively. The primary endpoint was angiographic in-scaffold late lumen loss at six months. This trial was registered at ClinicalTrials.gov (NCT04157153).

Findings

Between April 2020 and February 2022, 116 patients with 117 coronary artery lesions were enrolled. At six months, in-scaffold late lumen loss was 0.21 mm (SD 0.31). Intravascular ultrasound assessment showed preservation of the scaffold area (mean 7.59 mm² [SD 2.21] post-procedure vs 6.96 mm² [SD 2.48]) at six months) with a low mean neointimal area (0.02 mm² [SD 0.10]). Optical coherence tomography revealed that struts were embedded in the vessel wall and were already hardly discernible at six months. Target lesion failure occurred in one (0.9%) patient; a clinically driven target lesion revascularization was performed on post-procedure day 166. No definite or probable scaffold thrombosis or myocardial infarction was observed.

Interpretation

These findings show that the implantation of DREAMS 3G in de novo coronary lesions is associated with favorable safety and performance outcomes, comparable to contemporary drug-eluting stents.

Funding

This study was funded by BIOTRONIK AG.

Long-term outcomes of patients treated with sirolimus-eluting resorbable magnesium scaffolds: Insights from the SHERPA-MAGIC study

BACKGROUND

The resorbable magnesium scaffold (RMS) is a second-generation bioresorbable scaffold (BRS) that has shown conflicting results in previous studies. These findings suggest that patient selection and implantation technique may have an impact on clinical outcomes. This study aimed to investigate the safety and long-term effectiveness of RMS in a narrowly selected population.

METHODS

SHERPA-MAGIC is an investigator-driven, multicenter, prospective, single-arm study that enrolled patients undergoing BRS coronary implantation in 18 Italian centers. The present analysis considered the first 543 enrolled patients treated with RMS, with a minimum follow-up of 1 year. The study protocol included strict criteria for patient selection and standardization of RMS implantation. The primary outcome was the occurrence of the vessel-oriented composite endpoints (VOCE), including cardiac death, target vessel myocardial infarction, and ischemia-driven target vessel revascularization.

RESULTS

Overall, 635 vessels were treated. The 1-year cumulative occurrence of VOCE was 22 (3.5%, 95% CI 2.2%-5.2%), which was significantly lower than the prespecified estimation (from 5.5% to 8.5%). At the median follow-up of 3.5 [2.6-4.3] years, there were 3 (0.5%) cardiac deaths, 12 (1.9%) target vessel myocardial infarctions, and 33 (5.2%) ischemia-driven target vessel revascularizations. A total of 37 (5.8%, 95%CI 4.1%-7.9%) VOCEs were detected. Scaffold thrombosis occurred in 4 (0.6%, 95%CI 0.1%-1.6%) cases. Patient-level analysis confirmed the findings of the vessel-level analysis.

CONCLUSIONS

These results confirm the safety and performance of RMS technology. If confirmed in randomized controlled trials, they may rekindle interest in the use of scaffolds in daily practice.

Bioresorbable Magnesium-Based Stent: Real-World Clinical Experience and Feasibility of Follow-Up by Coronary Computed Tomography: A New Window to Look at New Scaffolds

(1) Background: The diagnostic accuracy of coronary computed tomography angiography (CCTA) for coronary artery disease (CAD) has greatly improved so CCTA represents a transition in the care of patients suffering from CAD. Magnesium-based bioresorbable stents (Mg-BRS) secure acute percutaneous coronary intervention (PCI) results without leaving, in the long term, a metallic caging effect. The purpose of this real-world study was to assess clinical and CCTA medium- and long-term follow-up of all our patients with implanted Mg-BRS. (2) Methods: The patency of 52 Mg-BRS implanted in 44 patients with de novo lesions (24 of which had acute coronary syndrome (ACS)) was evaluated by CCTA and compared to quantitative coronary angiography (QCA) post-implantation. (3) Results: ten events including four deaths occurred during a median follow-up of 48 months. CCTA was interpretable and in-stent measurements were successful at follow-up without being hindered by the stent strut's "blooming effect". Minimal in-stent diameters on CCTA were found to be 1.03 ± 0.60 mm smaller than the expected diameter after post-dilation on implantation (p < 0.05), a difference not found in comparing CCTA and QCA. (4) Conclusions: CCTA follow-up of implanted Mg-BRS is fully interpretable and we confirm the long-term Mg-BRS safety profile.

The Effects of Sirolimus and Magnesium on Primary Human Coronary Endothelial Cells: An In Vitro Study

Drug eluting magnesium (Mg) bioresorbable scaffolds represent a novel paradigm in percutaneous coronary intervention because Mg-based alloys are biocompatible, have adequate mechanical properties and can be resorbed without adverse events. Importantly, Mg is fundamental in many biological processes, mitigates the inflammatory response and is beneficial for the endothelium. Sirolimus is widely used as an antiproliferative agent in drug eluting stents to inhibit the proliferation of smooth muscle cells, thus reducing the occurrence of stent restenosis. Little is known about the potential interplay between sirolimus and Mg in cultured human coronary artery endothelial cells (hCAEC). Therefore, the cells were treated with sirolimus in the presence of different concentrations of extracellular Mg. Cell viability, migration, barrier function, adhesivity and nitric oxide synthesis were assessed. Sirolimus impairs the viability of subconfluent, but not of confluent cells independently from the concentration of Mg in the culture medium. In confluent cells, sirolimus inhibits migration, while it cooperates with Mg in exerting an anti-inflammatory action that might have a role in preventing restenosis and thrombosis.

Challenges of the newer generation of resorbable magnesium scaffolds: Lessons from failure mechanisms of the past generation

Bioresorbable scaffolds (BRS) were developed to overcome the obstacles of metallic stents, mostly related to sustained presence of metallic foreign body in the coronary vessel. Following earlier success of single-arm BRS studies, randomized controlled trials of Absorb bioresorbable vascular scaffold (Abbott Vascular, Santa Clara, CA, USA) showed poor long-term clinical outcomes, particularly in terms of scaffold thrombosis. BRS made from magnesium alloy provide a promising alternative in terms of radial force, strut thickness and, potentially lower thrombogenicity. A recent clinical study demonstrated that magnesium-based BRS seems to be promising with regards to the risk of scaffold thrombosis. In this review, our aim is to describe the issues that prevented Absorb BVS from achieving favorable outcomes, provide current status of existing BRS technologies and the challenges that newer generation BRSs need to overcome, and the results of clinical studies for commercially available magnesium-based BRS, which remain the only BRS actively studied in clinical practice.

Thrombosis and myocardial infarction: the role of bioresorbable scaffolds

Coronary stents have dramatically improved the treatment of coronary artery stenosis. In-stent-restenosis (ISR) and stent thrombosis (ST) pose major obstacles to the success of coronary stenting. Drug-eluting stents (DES) emerged as a major breakthrough in stenting and significantly reduced ISR. Despite taking dual antiplatelet therapy (DAPT), very late ST has remained a major obstacle in the success of DES. This occurs regardless of the type of polymer or antiproliferative agent in the contemporary stents. Such adverse events occur at a rate of approximately 2% to 3% per year after first year, which have been attributed to the strut fractures, loss of vessel compliance and vasomotion, and neoatherosclerosis. Fully bioresorbable scaffolds (BRS) have emerged in an effort to overcome these limitations leading to a "leave nothing behind" approach. While appealing, the initial experience with BRS technology was hampered by increased rates of BRS thrombosis compared with DES. In this review, we summarized underlying mechanisms leading to BRS failure and provided insights into optimizing BRS deployment with intravascular imaging. In addition, we outlined the perspectives of new generations BRS with thinner struts and new designs as well as alternative materials to improve outcome.

Effects of Altering Magnesium Metal Surfaces on Degradation In Vitro and In Vivo during Peripheral Nerve Regeneration

In vivo use of biodegradable magnesium (Mg) metal can be plagued by too rapid a degradation rate that removes metal support before physiological function is repaired. To advance the use of Mg biomedical implants, the degradation rate may need to be adjusted. We previously demonstrated that pure Mg filaments used in a nerve repair scaffold were compatible with regenerating peripheral nerve tissues, reduced inflammation, and improved axonal numbers across a short-but not long-gap in sciatic nerves in rats. To determine if the repair of longer gaps would be improved by a slower Mg degradation rate, we tested, in vitro and in vivo, the effects of Mg filament polishing followed by anodization using plasma electrolytic oxidation (PEO) with non-toxic electrolytes. Polishing removed oxidation products from the surface of as-received (unpolished) filaments, exposed more Mg on the surface, produced a smoother surface, slowed in vitro Mg degradation over four weeks after immersion in a physiological solution, and improved attachment of cultured epithelial cells. In vivo, treated Mg filaments were used to repair longer (15 mm) injury gaps in adult rat sciatic nerves after placement inside hollow poly (caprolactone) nerve conduits. The addition of single Mg or control titanium filaments was compared to empty conduits (negative control) and isografts (nerves from donor rats, positive control). After six weeks in vivo, live animal imaging with micro computed tomography (micro-CT) showed that Mg metal degradation rates were slowed by polishing vs. as-received Mg, but not by anodization, which introduced greater variability. After 14 weeks in vivo, functional return was seen only with isograft controls. However, within Mg filament groups, the amount of axonal growth across the injury site was improved with slower Mg degradation rates. Thus, anodization slowed degradation in vitro but not in vivo, and degradation rates do affect nerve regeneration.

Coronary Bifurcation Stenting: Review of Current Techniques and Evidence

BACKGROUND

Coronary bifurcation stenting constitutes 20% of all PCI performed. Given the extensive prevalence of bifurcation lesions, various techniques have sought to optimally stent the bifurcation to improve revascularization while also decreasing rates of stent thrombosis and lesion recurrence. Advanced techniques, such as planned two-stent approaches, have been shown to have improved outcomes but also require fluoroscopy and procedure time, posing an economic argument as well as a patient-outcome one.

OBJECTIVE

Because of the many strategies posited in the literature, it becomes essential to objectively evaluate evidence from randomized controlled trials and meta-analyses to help determine the optimal stenting strategy.

METHODS

We reviewed the clinical evidence on the efficacy of coronary bifurcation stenting.

RESULTS

In this paper, we review the most recent randomized controlled trials and meta-analyses on the efficacy of various stenting techniques and advances in stenting technologies published to gauge the current state of understanding and chart where the field is heading.

CONCLUSION

Bifurcation stenting is a maturing problem in the field of interventional cardiology that is adapting to the needs of the patients and advances in technology.

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

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

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

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

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

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

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Development in the assessment of stent performance in vivo.

A Biodegradable Metal-Polymer Composite Stent Safe and Effective on Physiological and Serum-Containing Biomimetic Conditions

The new-generation coronary stents are expected to be biodegradable, and then the biocompatibility along with biodegradation becomes more challenging. It is a critical issue to choose appropriate biomimetic conditions to evaluate biocompatibility. Compared with other candidates for biodegradable stents, iron-based materials are of high mechanical strength, yet have raised more concerns about biodegradability and biocompatibility. Herein, a metal-polymer composite strategy is applied to accelerate the degradation of iron-based stents in vitro and in a porcine model. Furthermore, it is found that serum, the main environment of vascular stents, ensured the safety of iron corrosion through its antioxidants. This work highlights the importance of serum, particularly albumin, for an in vitro condition mimicking blood-related physiological condition, when reactive oxygen species, inflammatory response, and neointimal hyperplasia are concerned. The resultant metal-polymer composite stent is implanted into a patient in clinical research via interventional treatment, and the follow-up confirms its safety, efficacy, and appropriate biodegradability.

Coronary Computed Tomography Angiography for the Assessment of Sirolimus-Eluting Resorbable Magnesium Scaffold

Background: Little evidence to date has described the feasibility and diagnostic accuracy of coronary computed tomography angiography (CCTA) with noninvasive fractional flow reserve (CT-FFR) in coronary vessels with resorbable magnesium scaffold (RMS). Methods: The SHERPA-MAGIC is a prospective study enrolling patients receiving RMS. The present analysis considered patients undergoing CCTA 18 months after the index procedure. CCTA images were employed to investigate reabsorption status, luminal measurements, and noninvasive FFR. Three-year follow-up was available for all patients. Results: Overall, 26 patients with a total of 29 coronary arteries treated with 35 RMS were considered. The most frequently involved vessel was left anterior descendent (LAD). Median stent length was 25 (20–25) mm, with a median diameter of 3 (3–3.5) mm. At 18-month CCTA, all scaffolded segments were patent. Complete RMS reabsorption was observed in 27 (93%, 95% CI 77–99%) cases. Median minimal lumen diameter (MLD) and area (MLA) of the scaffolded segments were 2.5 [2.1–2.8] mm and 6.4 [4.4–8.4] mm², respectively. Median CT-FFR was 0.88 [0.81–0.91]. Only one (3.5%) vessel showed a flow-limiting CT-FFR value ≤0.80. During the 3-year follow-up, only one (4%) adverse event was observed. Conclusions: In patients undergoing RMS implantation, CCTA including noninvasive CT-FFR evaluation is feasible and allows investigation of long-term RMS performance.

The bioresorbable magnesium scaffold (Magmaris)-State of the art: From basic concept to clinical application

Since its introduction to clinical practice, coronary artery stent implantation has become a crucial part of the therapy of coronary artery disease (CAD). Despite the undeniable evolution of percutaneous coronary revascularization procedures, drug-eluting stent (DES) technology shows some limitations. To overcome these limitations bioresorbable vascular scaffolds (BRS) were designed as a vessel-supporting technology allowing for anatomical and functional restoration of the vessel after the scaffold intended resorption. Various materials have been proposed as the basis of the scaffold backbone. In this narrative review, we present second-generation magnesium-alloy bioresorbable scaffold devices (Magmaris; Biotronik). Additionally, we discuss available preclinical and clinical data regarding this new magnesium BRS.

Five-year clinical outcomes using the bioresorbable vascular scaffold: Insights from the FRANCE ABSORB registry

BACKGROUND

Randomized trials comparing the first-generation absorb bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, CA, USA) with a drug-eluting stent showed a moderate but significant increase in the rate of 3-year major adverse cardiac events and scaffold thrombosis, followed by a decrease in adverse events after 3 years.

AIM

The objective of this study was to assess the 5-year outcomes of patients treated with at least one absorb BVS and included in the FRANCE ABSORB registry.

METHODS

All patients treated in France with an absorb BVS were prospectively included in a large nationwide multicentre registry. The primary efficacy outcome was the occurrence of 5-year major adverse cardiac events. Secondary efficacy outcomes were the rates of 5-year target vessel revascularization and definite/probable scaffold thrombosis.

RESULTS

Between September 2014 and April 2016, 2,070 patients were included in 86 centres (mean age 55±11 years; 80% men; 49% with acute coronary syndrome). The rates of 1-, 3- and 5-year major adverse cardiac events were 3.9%, 9.4% and 12.1%, respectively (including cardiac death in 2.5% and target vessel revascularization in 10.4%). By multivariable analysis, diabetes, oral anticoagulation, the use of multiple Absorb BVSs and the use of a 2.5mm diameter absorb BVS were associated with 5-year major adverse cardiac events. The rates of 1-, 3- and 5-year definite/probable scaffold thrombosis were 1.5%, 3.1% and 3.6%, respectively. By multivariable analysis, older age, diabetes, anticoagulation at discharge and the use of a 2.5mm diameter absorb BVS were associated with 5-year scaffold thrombosis.

CONCLUSIONS

Absorb BVS implantation was associated with low rates of 1-year major adverse cardiac events, which increased significantly at 3-year follow-up. There was a clear decrease in the rates of scaffold thrombosis and major adverse cardiac events after 3 years.

Outcomes of the two generations of bioresorbable scaffolds (Magmaris vs. Absorb) in acute coronary syndrome in routine clinical practice

BACKGROUND

Acute coronary syndrome (ACS) as a clinical manifestation of coronary artery disease (CAD) remains a significant cause of mortality and morbidity, as reported worldwide annually. The second generation of drug-eluting stents (DES) is a gold standard in percutaneous interventions in ACS patients however, permanent caging of the vessel with metallic DES has some drawbacks. Bioresorbable vascular scaffolds (BRS) were designed as a temporal vessel-supporting technology allowing for anatomical and functional restoration. Nevertheless, following the initial encouraging reports, numerous concerns about the safety of BRS occurred.

METHODS

In this study, a 1-year performance of 193 patients with magnesium BRS - Magmaris (Biotronik, Berlin, Germany) was evaluated in comparison to 160 patients with polymer BRS - Absorb (Abbott-Vascular, Chicago, USA) in the non-ST-segment elevation-ACS setting.

RESULTS

The Magmaris, when compared to Absorb showed a significantly lower rate of primary endpoint (death from cardiac causes, myocardial infarction, stent thrombosis) as well as target lesion failure in 30-day and 1 year follow-up. In the Absorb group, a significantly higher rate of stent thrombosis was observed.

CONCLUSIONS

Data from the present study suggests encouraging safety a profile and more favorable clinical outcomes of Magnesium BRS in comparison to the polymer Absorb - BRS.

Long-Term Outcomes After Implantation of Magnesium-Based Bioresorbable Scaffolds—Insights From an All-Comer Registry

Background

The magnesium-based sirolimus-eluting bioresorbable scaffold (Mg-BRS) Magmaris™ showed promising clinical outcomes, including low rates of both the target lesion failure (TLF) and scaffold thrombosis (ScT), in selected study patients. However, insights regarding long-term outcomes (&gt;2 years) in all-comer populations remain scarce.

Methods

We analyzed data from a single-center registry, including patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS), who had undergone percutaneous coronary intervention (PCI) using the Mg-BRS. The primary outcome comprised the device-oriented composite endpoint (DoCE) representing a hierarchical composite of cardiac death, ScT, target vessel myocardial infarction (TV-MI), and clinically driven target lesion revascularization (TLR) up to 5 years.

Results

In total, 84 patients [mean age 62 ± 11 years and 63 (75%) men] were treated with the Mg-BRS devices between June 2016 and March 2017. Overall, 101 lesions had successfully been treated with the Mg-BRS devices using 1.2 ± 0.4 devices per lesion. Pre- and postdilatation using dedicated devices had been performed in 101 (100%) and 98 (97%) of all the cases, respectively. After a median follow-up time of 62 (61–64) months, 14 (18%) patients had experienced DoCEs, whereas ScT was encountered in 4 (4.9%) patients [early ScTs (&lt;30 days) in three cases and two fatal cases]. In 4 (29%) of DoCE cases, optical coherence tomography confirmed the Mg-BRS collapse and uncontrolled dismantling.

Conclusion

In contradiction to earlier studies, we encountered a relatively high rate of DoCEs in an all-comer cohort treated with the Mg-BRS. We even observed scaffold collapse and uncontrolled dismantling. This implicates that this metal-based BRS requires further investigation and may only be used in highly selected cases.

Overcoming challenges in refining the current generation of coronary stents

INTRODUCTION

Late stent thrombosis caused by delayed vascular healing and prolonged local inflammation were major drawbacks of 1^st generation drug-eluting stents (DES). Strut design, biocompatibility of polymer, and drug-release profiles were improved in 2^nd and 3rdgeneration DES. Accordingly, the indications for percutaneous coronary intervention with DES have been expanded to more complex patients and lesions. Despite these improvements, significant barriers such as greater flexibility in the duration of dual-antiplatelet therapy (DAPT) as well as reducing long-term stent-related events remain. To achieve ideal short- and long-term results, these existing limitations need to be overcome.

AREAS COVERED

We will discuss the current limitations of coronary DES and how they might be overcome from pathological and clinical viewpoints.

EXPERT OPINION

Optimizing DAPT duration after stent implantation and prevention of in-stent neoatherosclerosis are two major issues in current DES. Overcoming these drawbacks is a prerequisite toward achieving better short- and long-term clinical outcomes. New technologies including platform design, polymer types, and anti-proliferative agent itself might lead to further improvements. Although the initial experience with bioresorbable scaffold/stents (BRS) was disappointing, positive results of clinical studies regarding novel BRS are raising expectations. Overall, further device innovation is desired for overcoming the limitations of current DES.

Comparison of a Bioresorbable, Magnesium-Based Sirolimus-Eluting Stent with a Permanent, Everolimus-Eluting Metallic Stent for Treating Patients with Acute Coronary Syndrome: the PRAGUE-22 Study

Background

Magnesium-based bioresorbable Magmaris stents are rapidly resorbed. Few randomized studies have evaluated the efficacy of such stents in patients with acute coronary syndrome.

Aim

To investigate late lumen loss as assessed via quantitative coronary angiography (QCA) and optical coherence tomography (OCT) in patients with acute coronary syndrome treated with Magmaris stents or permanent, everolimus-eluting metallic Xience stents.

Methods and Results

This PRAGUE-22 study was a two-centre, investigator-initiated, randomized study. Fifty patients were randomized based on the inclusion criteria for acute coronary syndrome and the anatomical suitability to receive Magmaris or Xience stents. The patient characteristics did not differ between the Magmaris group (n = 25) and Xience group (n = 25). The mean ages were 57.0 ± 10.5 vs. 55.5 ± 9.2 years (p = 0.541) and the total implanted stent length was 24.6 ± 10.7 mm vs. 27.6 ± 11.1 mm (p = 0.368), respectively. Four clinical events occurred in the Magmaris group and one in the Xience group during 12 months of follow-up. The extent of late lumen loss (assessed via QCA) at 12 months was greater in the Magmaris group than in the Xience group (0.54 ± 0.70 vs. 0.11 ± 0.37 mm; p = 0.029). The late lumen loss diameter (measured via OCT) in the Magmaris group was also significantly larger than that in the Xience group (0.59 ± 0.37 vs. 0.22 ± 0.20 mm; p = 0.01).

Conclusion

Implantation of a magnesium-based bioresorbable stent in patients with acute coronary syndrome is associated with a greater extent of late lumen loss at the 12-month follow-up compared with implantation of a permanent, everolimus-eluting metallic stent.

Trial Registration: ISRCTN89434356

Sustained safety and performance of a second-generation sirolimus-eluting absorbable metal scaffold: Long-term data of the BIOSOLVE-II first-in-man trial at 5 years

BACKGROUND

Permanent drug-eluting stents are associated with a steady increase of late complications attributed to persistent inflammation and poor vessel remodelling. Bioresorbable scaffolds have been developed to overcome such long-term limitations by providing temporary vessel support and disappearing thereafter. We aimed to assess the long-term outcomes of an absorbable metallic scaffold at 5 years.

METHODS

BIOSOLVE-II is an international, multi-centre, first-in-human study assessing the safety and performance of the sirolimus-eluting absorbable metal scaffold DREAMS 2G (commercial name Magmaris) in patients with a maximum of two de novo lesions. After 3 years, follow-up was extended to 5 years with the endpoints target lesion failure and rate of definite or probable stent thrombosis.

RESULTS

123 patients with 123 lesions were enrolled. Lesions were 12.6 ± 4.5 mm long and 2.7 ± 0.4 mm in diameter, 43.4% were class B2/C lesions, and calcification was moderate to severe in 10.6%. At 5 years, 5.4% of patients had stable angina and 94.6% had no symptoms or ischemia. Target lesion failure rate was 8.0% [95% CI:4.2;14.9], reflecting 2 cardiac deaths, 2 target-vessel myocardial infarction, and 6 clinically-driven target lesion revascularizations. Only one target lesion failure occurred beyond 3 years; a target-vessel myocardial infarction with clinically-driven TLR on post-procedure day 1157. One additional non-cardiac death beyond 3 years due to renal failure was reported on day 1777. No definite or probable scaffold thrombosis was observed.

CONCLUSION

The Magmaris scaffold showed favourable long-term safety and clinical performance with low target lesion failure rates and absence of definite or probable scaffold thrombosis throughout 5 years.

ANNOTATED TABLE OF CONTENTS

BIOSOLVE-II is a prospective, multi-centre, first-in-man trial enrolling 123 patients with de novo coronary artery lesions. Target lesion failure rate at 5 years was low (8.0%), including 2 cardiac deaths, 2 target-vessel myocardial infarction and 6 clinically-driven target lesion revascularizations. No definite or probable scaffold thrombosis was observed.

BIOSOLVE-IV-registry: Safety and performance of the Magmaris scaffold: 12-month outcomes of the first cohort of 1,075 patients

OBJECTIVES

We aimed to assess the safety and performance of the Magmaris sirolimus-eluting bioresorbable magnesium scaffold in a large patient population.

BACKGROUND

Magmaris has shown good outcomes in small-sized controlled trials, but further data are needed to confirm its usability, safety, and performance.

METHODS

BIOSOLVE-IV is an international, single arm, multicenter registry including patients with a maximum of two single de novo lesions. Follow-up is scheduled up to 5 years; the primary outcome is target lesion failure (TLF) at 12 months.

RESULTS

A total of 1,075 patients with 1,121 lesions were enrolled. Mean patient age was 61.3 ± 10.5 years and 19.2% (n = 206) presented with non-ST-elevation myocardial infarction (NSTEMI). Lesions were 3.2 ± 0.3 mm in diameter and 14.9 ± 4.2 mm long; 5.1% (n = 57) were bifurcation lesions. Device success was 97.3% (n = 1,129) and procedure success 98.9% (n = 1,063). The Kaplan-Meier estimate of TLF at 12 months was 4.3% [95% confidence interval, CI: 3.2, 5.7] consisting of 3.9% target lesion revascularizations, 0.2% cardiac death, and 1.1% target-vessel myocardial infarction. Definite/probable scaffold thrombosis occurred in five patients (0.5% [95% CI: 0.2, 1.1]), thereof four after early discontinuation of antiplatelet/anticoagulation therapy.

CONCLUSION

BIOSOLVE-IV confirms the safety and performance of the Magmaris scaffold in a large population with excellent device and procedure success and a very good safety profile up to 12 months in a low-risk population.

Recent advances and directions in the development of bioresorbable metallic cardiovascular stents: Insights from recent human and in vivo studies

Over the past two decades, significant advancements have been made regarding the material formulation, iterative design, and clinical translation of metallic bioresorbable stents. Currently, magnesium-based (Mg) stent devices have remained at the forefront of bioresorbable stent material development and use. Despite substantial advances, the process of developing novel absorbable stents and their clinical translation is time-consuming, expensive, and challenging. These challenges, coupled with the continuous refinement of alternative bioresorbable metallic bulk materials such as iron (Fe) and zinc (Zn), have intensified the search for an ideal absorbable metallic stent material. Here, we discuss the most recent pre-clinical and clinical evidence for the efficacy of bioresorbable metallic stents and material candidates. From this perspective, strategies to improve the clinical performance of bioresorbable metallic stents are considered and critically discussed, spanning material alloy development, surface manipulations, material processing techniques, and preclinical/biological testing considerations. STATEMENT OF SIGNIFICANCE: Recent efforts in using Mg, Fe, and Zn based materials for bioresorbable stents include elemental profile changes as well as surface modifications to improve each of the three classes of materials.  Although a variety of alloys for absorbable metallic stents have been developed, the ideal absorbable stent material has not yet been discovered. This review focuses on the state of the art for bioresorbable metallic stent development. It covers the three bulk materials used for degradable stents (Mg, Fe, and Zn), and discusses their advances from a translational perspective. Strategies to improve the clinical performance of bioresorbable metallic stents are considered and critically discussed, spanning material alloy development, surface manipulations, material processing techniques, and preclinical/biological testing considerations.

Bioresorbable Scaffolds in Percutaneous Coronary Intervention: Facing Old Problems, Raising New Hopes

PURPOSE OF REVIEW

In this review, we discuss about the reasons behind the failure of the Absorb bioresorbable vascular scaffold (BVS) device and about the challenges the future holds for the next generation of the bioresorbable scaffold (BRS) technology.

RECENT FINDINGS

Absorb BVS was burdened by intrinsic structural limitations which resulted in augmented rates of device thrombosis and clinical adverse events compared to current-generation metallic stent. Nevertheless, new generation devices with novel design and materials are in development. Second generation BRS have enhanced mechanical strength, smaller footprints, less thrombogenicity and modified bioresorption. These features, paired with proper patient and lesion selection and optimal "user-friendly" implant techniques, could possibly overcome the previous BRS generation limitations, rekindling physicians, and industry interest on this promising technology.