Bioresorbable stents: Is the game over?

Abstract

Bioresorbable scaffolds (BRS) emerged as an alternative to conventional stents with a fundamental idea, to avoid a permanent metallic cage with all its harmful effects on the vessel. The Absorb BVS was the first widely studied device with the promising concept of performing a percutaneous coronary intervention, giving the necessary initial support to maintain vessel integrity and avoid acute vessel thrombosis. After a period, complete resorption of the device without leaving in the vessel any metallic structure would theoretically offer several benefits as the reduction of the inflammatory response and recovering normal vasomotor function, recovering access of jailed side-branches and segments for surgical revascularization, and the reduction of very late stent thrombosis derived from late acquired malapposition. However, cumulative evidence from the different absorb randomized trials (ABSORB II, ABSORB III, ABSORB China, ABSORB Japan) raised significant concerns, due to an elevated rate of scaffold thrombosis, target lesion failure and target vessel failure, when compared to contemporary everolimus drug-eluting stents. Several mechanisms arose explaining scaffold failure; some were strictly related to the device itself, and others related to the operator and the lesion itself. Newer generation BRS are under development targeting the main limitations of the ABSORB BVS, mainly focusing on reducing strut thickness, improving the mechanical structure with faster resorption times, and a better crossing profile. The story of BRS is not over yet, with ongoing refinements in the quest for the ideal stent.

Keywords: Bioresorbable vascular scaffold; Drug eluting stent; Scaffold restenosis; Scaffold thrombosis.