Current situation and overview of resorbable magnesium scaffolds: a perspective for overcoming the remaining issues of polymeric bioresorbable scaffold

Bioresorbable scaffolds (BRS) were developed as an innovative solution to overcome the limitations of metallic stents. While polymeric BRS initially demonstrated comparable clinical outcomes to drug-eluting stent (DES) in clinical trials, subsequent large-scale studies revealed that patients implanted with polymeric BRS experienced higher rates of scaffold thrombosis (ScT) and target lesion failure compared to those with metallic stents. Resorbable magnesium scaffolds (RMS) have emerged as a promising alternative owing to magnesium's natural degradability and favorable mechanical properties. Learning from the mechanism of polymeric BRS failure and through continuous improvements, recent clinical trials have shown promising clinical performance for RMS technology. However, comparative studies between RMS and DES have continued to highlight the remaining challenges with RMS, particularly in regard to late lumen loss. Recent advancements in third-generation RMS show improvements in strut thickness and homogeneous degradation, which enhances sustained structural integrity throughout the degradation process. Based on encouraging results from a first-in-human trial of the latest version of RMS, a randomized controlled trial has been initiated to compare the outcomes between metallic stents and the latest RMS, with patient enrollment already underway. This review aims to explore the limitations of polymeric BRS and provide an overview of the current developments and future potential of magnesium-based BRS.

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.

Current perspectives on bioresorbable scaffolds in coronary intervention and other fields

Introduction: The first-generation bioresorbable scaffolds (BRSs) had a large strut profile to compensate for the insufficient radial strength of bioresorbable polymer materials, resulting in higher scaffold thrombosis rates than conventional drug-eluting stents. To improve the clinical safety and efficacy, the new generation BRSs have been improved by optimal structure design, post-processing of bioresorbable polymer materials, or altering bioresorbable metallic alloys.Areas covered: This review summarizes the lessons learned from the first-generation BRS, updates the clinical outcomes of trials evaluating ABSORB bioresorbable vascular scaffold at long-term and bioresorbable metallic alloy-based devices, and examines recent outcomes of BRS treated in STEMI patients. This review also provides an overview of the current clinical data of seven BRSs manufactured in Asia, and of the BRSs extended application in other clinical arenas.Expert opinion: Drawbacks of the first-generation BRSs need to be addressed by the next generation of these stents with novel materials and technologies. Clinical research, including randomized controlled trials, are required to further evaluate BRSs application in coronary artery disease. The encouraging results of BRSs innovation applied in the peripheral arteries and gastrointestinal tracts support other potential clinical applications of BRS technology.