Bioresorbable vascular scaffolds for the treatment of coronary artery disease: what have we learned from randomized-controlled clinical trials?

Although current everolimus-eluting coronary stents have shown improved event-free survival within the first year following implantation compared with bare-metal stents or earlier generation drug-eluting stents, they remain associated with an ongoing risk for adverse outcomes (thrombosis, myocardial infarction, and restenosis) beyond 1 year at rates similar to those observed following bare-metal stent deployment. This ongoing very late hazard has been attributed to the permanent presence of the metal frame and/or polymer in these stents. The Absorb everolimus-eluting bioresorbable vascular scaffold (Absorb BVS) has been developed to provide mechanical support and drug-delivery functions similar to metallic drug-eluting stents, followed by complete resorption with recovery of more normal vascular structure and function, thus avoiding the limitations associated with permanent metallic endovascular prostheses. Absorb BVS has shown safety and efficacy in the dedicated clinical trial development program of Abbott Vascular and in an array of investigator-sponsored studies involving a broad spectrum of clinical (patient) as well as coronary anatomic complexity. Longer-term evidence, largely limited to single-arm studies, appears to reflect durable safety and efficacy and suggests Absorb BVS to be an attractive therapeutic option. Interim evidence from a series of randomized-clinical trials (RCTs) comparing Absorb BVS with the Xience cobalt-chromium metallic everolimus-eluting stent has shown noninferiority of Absorb BVS with respect to target lesion failure (composite occurrence of cardiac death, target vessel-related myocardial infarction, and ischemia-driven target lesion revascularization) beyond the first year, with no statistically significant differences in other safety/efficacy measures. However, concerns do exist in terms of increased rates of scaffold thrombosis, the risk for which may be mitigated by improved patient and lesion selection, procedural technique, and device iteration. We provide an overview of the evolution of percutaneous coronary intervention, in-vivo characterization of Absorb BVS resorption, and a summary with a critical evaluation of available evidence from RCTs, pooled analyses, and meta-analyses of RCTs for the safety and efficacy of Absorb BVS obtained primarily following the treatment of noncomplex coronary lesions in patients with stable ischemic heart disease and/or stabilized acute coronary syndromes.