The Current Literature on Bioabsorbable Stents: a Review.

PURPOSE OF REVIEW: The purpose of this review is to explore the evolution of the coronary stent, from the advent of bare-metal stents, to the newest adopted technology of bioresorbable vascular scaffolds (BVS) used in bioresorbable stents. To date, there have been conflicting data regarding the safety and efficacy of BVS stents, especially when compared to current-generation drug-eluting stents (DES). This review will cover the data that exist regarding current BVS stents, as well as the active clinical trials for future iterations of BVS. RECENT
FINDINGS: The ABSORB BVS, the most widely circulated stent of its class, was promised to decrease rates of stent thrombosis and target vessel revascularization. Several randomized control trials, however, found the opposite to be true, with the ABSORB BVS demonstrating higher rates of thrombosis, target vessel revascularization, and even target lesion myocardial infarctions when compared to current-generation DES. These data caused the product to be pulled from all markets, leaving the field with uncertainty as to the role of BVS in coronary interventions. Coronary stents have evolved significantly from 1977, when they were first introduced. The original bare-metal stent was later fitted with a drug-eluting polymer, to prevent restenosis and thrombosis over time. Subsequent iterations of the stent attempted to further mitigate that risk by replacing the durable polymer to one that is bioresorbable. The final step in this progression was to create a stent that was fully bioresorbable, which Abbott did with the creation of their ABSORB BVS stent. The product, however, was found to perform poorly when compared to current-generation drug-eluting stents, with several trials showing high rates of stent thrombosis (ST), late stent thrombosis (LST), target-lesion myocardial infarction, and target vessel revascularization. Observational studies of BVS stents have proposed several mechanisms for their thrombogenicity, including higher stent-strut profiles leading to turbulent flow, low radial strength leading to strut disruption, and a higher propensity for neoatherosclerosis. Given the failure of the first-generation BVS stent, but the lingering desire for fully bioresorbable scaffolds, various manufacturers have proposed their solutions with new stents. Until data from their clinical trials emerge, it remains unclear whether fully bioresorbable stents will play any role in coronary interventions.