Evaluating magnesium alloy WE43 for bioresorbable coronary stent applications

Biodegradable stents, especially those composed of magnesium alloy-based materials, can provide a temporary scaffold that support vessels while naturally resorbing in the body after the targeted vessel heals, thereby preventing the restenosis and late thrombosis issues caused by their metallic predecessors. However, due to limitations in the intrinsic mechanical properties of magnesium, further investigation is required to optimize its degradation property, as well as the design, geometry and strut thickness to improve conformability in stent applications. This study aimed to investigate experimentally the degradation property of magnesium alloy WE43 and to optimize the stent geometry through parametric studies using the finite element method. Results of the degradation testing showed that the WE43 with a secondary polycaprolactone dip-coating offered a greater resistance to biodegradation and increased the lifespan of the stent. On average, the resistance to biodegradation increased by 5% in the WE43 magnesium alloy compared with its counterpart lacking any surface coating. The parametric studies have indicated that the stent with honeycomb geometry and a radial thickness of 0.15 mm had demonstrated promising mechanical performance with minimal dog-boning, foreshortening and recoil.