Everolimus-Eluting Bioresorbable Scaffold Versus Everolimus-Eluting Metallic Stents (original) (raw)

Annals of internal medicine, 2016

Abstract

TO THE EDITOR: Zhang and colleagues (1) conclude that everolimus-eluting bioresorbable vascular scaffolds (BVSs) pose a greater risk for stent thrombosis and myocardial infarction than everolimus-eluting metallic stents (EESs). This conclusion is somewhat misleading, because their best evidence was obtained from randomized, controlled trials (RCTs), not observational studies (2). In their analysis, summary results were not significant for RCTs. Their overall summary result (combined for observational studies and RCTs) seems to have been driven by data from observational studies. Observational studies cannot provide evidence of cause and effectthey can only provide evidence of some relationship (between exposure and outcome) (2). Discrepancies between the results of RCTs and those of observational studies are probably caused by unmeasured confounding factors in the observational studies, where each patient's treatment is specifically chosen rather than randomly assigned. Because 1 of the potential benefits of BVSs is believed to be lower risk for late stent thrombosis, patients in observational studies who were predisposed to stent thrombosis may have preferentially received these devices (3, 4). Finally, Zhang and colleagues performed metaregression for several variables and found that none of them affected the risk for stent thrombosis. However, they did not report interaction statistics for 2 important variablesuse of an intravascular imaging device and routine high-pressure postinflationboth of which are known to affect risk for stent thrombosis with BVSs (3, 4). Current BVSs are manufactured with thicker struts (typically 150 to 200 m in width) than new-generation EESs, leading to greater strut protrusion and thus greater turbulence and platelet activation (3, 4). Because of these physical characteristics, it is recommended that greater attention be placed on procedural techniques with BVSs, including use of routine intravascular imaging (that is, intravascular ultrasonography or optical coherence tomography) and high-pressure postdilation. A recent multicenter registry in which a dedicated protocol for BVS implantation significantly reduced the risk for associated stent thrombosis supports the importance of these optimizing techniques (4). They unfortunately were not frequently used in the ABSORB III trial (5), a major driver in the event rate for stent thrombosis in Zhang and colleagues' meta-analysis of the RCTs (1). In this trial, intravascular imaging was used only 11% of the time and postdilation was done 65% of the time (5). Such infrequent use of optimization techniques could have contributed to the increased incidence of stent thrombosis with BVSs.

Camilla Fox Maule hasn't uploaded this paper.

Let Camilla know you want this paper to be uploaded.

Ask for this paper to be uploaded.