Long-term safety of an everolimus-eluting bioresorbable vascular scaffold and the cobalt-chromium XIENCE v stent in a porcine coronary artery model

Background-The Absorb everolimus-eluting bioresorbable vascular scaffold (Absorb) has shown promising clinical results; however, only limited preclinical data have been published. We sought to investigate detailed pathological responses to the Absorb versus XIENCE V (XV) in a porcine coronary model with duration of implant extending from 1 to 42 months. Methods and Results-A total of 335 devices (263 Absorb and 72 XV) were implanted in 2 or 3 main coronary arteries of 136 nonatherosclerotic swine and examined by light microscopy, scanning electron microscopy, pharmacokinetics, and gel permeation chromatography analyses at various time points. Vascular responses to Absorb and XV were largely comparable at all time points, with struts being sequestered within the neointima. Infammation was mild to moderate (with absence of infammation at 1 month) for both devices, although the scores were greater in Absorb at 6 to 36 months. Percent area stenosis was signifcantly greater in Absorb than XV at all time points except at 3 months. The extent of fbrin deposition was similar between Absorb and XV, which peaked at 1 month and decreased rapidly thereafter. Histomorphometry showed expansile remodeling of Absorb-implanted arteries starting after 12 months, and lumen area was signifcantly greater in Absorb than XV at 36 and 42 months. These changes correlated with dismantling of Absorb seen after 12 months. Gel permeation chromatography analysis confrmed that degradation of Absorb was complete by 36 months. Conclusions-Absorb demonstrates comparable long-term safety to XV in porcine coronary arteries with mild to moderate infammation. Although Absorb was associated with greater percent stenosis relative to XV, expansile remodeling was observed after 12 months in Absorb with signifcantly greater lumen area at ≥36 months. Resorption is considered complete at 36 months.