Bioresorbable metals in cardiovascular stents: Material insights and progress

The use of bioresorbable stents (BRS) was envisioned as the fourth revolution in interventional cardiology due to its potential benefits such as restoration of vasomotion and elimination of late adverse event after stent degradation. However, the clinical outcomes of Abbott's Vascular polymer-based Bioresorbable Vascular Scaffold (BVS) have demonstrated a higher rate of scaffold thrombosis, casting uncertainties over long-term use of the device. This has encouraged the development of bioresorbable stents fabricated from resorbable metals such as magnesium-, zinc- and iron-based alloys, with the promise of improved mechanical strength and biocompatibility. The review is categorised into the three main sections, namely: Fundamentals of resorbable metals, Benchtop and preclinical evaluation of the resorbable metals and Clinical progress of a magnesium-based BRS. The alloying and metallurgical processes were discussed to understand how they affect the mechanical and corrosion behavior of resorbable metals (magnesium-, zinc- and iron-based alloys). Key results from various in vitro and preclinical studies were discussed to provide insights on their potential as BRS candidates in terms of biocompatibility and degradation profile. Lastly, results from the magnesium-based BRS (Magmaris, CE-marked) summarized the current status of research in human clinical trials.