How does the failure of Absorb apply to the other bioresorbable scaffolds? An expert review of first-in-man and pivotal trials.

The Absorb bioresorbable scaffold (BRS), the most studied device among all BRS, suffered a major setback following the negative results of the ABSORB trials. However, approximately 34 BRSs from 22 companies are currently under development. The potential device-specific factors related to the increased event rate in Absorb were: 1) weak mechanical properties, 2) larger strut thickness (less embedment and larger protrusion) and width (larger footprint) predisposing to underexpansion/protrusion of struts, eventually resulting in increased thrombogenicity, and 3) longer bioresorption time combined with failure of encapsulation of struts before the dismantling process ensues. Given the diversity of bioresorbable materials (even amongst PLLA), and the different mechanical properties and bioresorption profiles of each new BRS, one could expect considerable difference in early and late clinical outcomes. As a matter of fact, data from first-in-man (FIM) and pivotal trials have demonstrated variable clinical results. Indeed, early clinical evidence from FIM trials does not support a class effect. However, the absence of a comparator precludes us from drawing definitive conclusions. Further clinical evidence should confirm the absence (or presence) of a class effect.