Overlapping meta-analyses of bioresorbable vascular scaffolds versus everolimus-eluting stents: bringing clarity or confusion?

The ABSORB (Abbot Vascular, Santa Clara, CA, USA) bioresorbable vascular scaffold (BVS) has been conceived to address some residual shortcomings of metallic drug-eluting stents (DES), including very late thrombosis and loss of vasomotion due to permanent caging of the coronary vessel. In Europe, BVSs were approved in 2011 mainly based on data from the ABSORB study, a two-stage single-arm investigation with multimodal imaging assessment including a total of 131 patients (1,2). To further investigate the device in a broader population and support European commercialization and reimbursement activities, the manufacturer initiated ABSORB II, a randomized controlled trial of 501 patients, where BVSs were tested on two surrogate co-primary endpoints (i.e., vasomotion and late lumen loss) against the cobalt-chromium XIENCE (Abbott Vascular, Santa Clara, CA, USA) everolimus-eluting stent (EES) (3). Interim 1-year results of ABSORB II have been published in 2015, showing no significant differences between BVSs and EESs, but these findings are at best hypothesis generating, due to the low statistical power of the study for clinical endpoints (4).