Vascular Response of the Segments Adjacent to the Proximal and Distal Edges of the ABSORB Everolimus-Eluting Bioresorbable Vascular Scaffold: 6-Month and 1-Year Follow-Up Assessment A Virtual Histology Intravascular Ultrasound Study From the First-in-Man ABSORB Cohort B Trial

Objectives This study sought to investigate in vivo the vascular response at the proximal and distal edges of the second-generation ABSORB everolimus-eluting bioresorbable vascular scaffold (BVS). Background The edge vascular response after implantation of the BVS has not been previously investigated. Methods The ABSORB Cohort B trial enrolled 101 patients and was divided into B-1 (n = 45) and B-2 (n = 56) subgroups. The adjacent (5-mm) proximal and distal vessel segments to the implanted ABSORB BVS were investigated at either 6 months (B-1) or 1 year (B-2) with virtual histology intravascular ultrasound (VH-IVUS) imaging. Results At the 5-mm proximal edge, the only significant change was modest constrictive remodeling at 6 months (Delta vessel cross-sectional area: -1.80% [-3.18; 1.30], p < 0.05), with a tendency to regress at 1 year (Delta vessel cross-sectional area: -1.53% [-7.74; 2.48], p = 0.06). The relative change of the fibrotic and fibrofatty (FF) tissue areas at this segment were not statistically significant at either time point. At the 5-mm distal edge, a significant increase in the FF tissue of 43.32% [-19.90; 244.28], (p < 0.05) 1-year post-implantation was evident. The changes in dense calcium need to be interpreted with caution since the polymeric struts are detected as "pseudo" dense calcium structures with the VH-IVUS imaging modality. Conclusions The vascular response up to 1 year after implantation of the ABSORB BVS demonstrated some degree of proximal edge constrictive remodeling and distal edge increase in FF tissue resulting in nonsignificant plaque progression with adaptive expansive remodeling. This morphological and tissue composition behavior appears to not significantly differ from the behavior of metallic drug-eluting stents at the same observational time points. (J Am Coll Cardiol Intv 2012;5:656-65) (c) 2012 by the American College of Cardiology Foundation