Scaffold and Edge Vascular Response Following Implantation of Everolimus-Eluting Bioresorbable Vascular Scaffold

Objectives This study sought to investigate the in-scaffold vascular response (SVR) and edge vascular response (EVR) after implantation of an everolimus-eluting bioresorbable scaffold (BRS) using serial optical coherence tomography (OCT) imaging. Background Although studies using intravascular ultrasound have evaluated the EVR in metal stents and BRSs, there is a lack of OCT-based SVR and EVR assessment after BRS implantation. Methods In the ABSORB Cohort B (ABSORB Clinical Investigation, Cohort B) study, 23 patients (23 lesions) in Cohort B1 and 17 patients (18 lesions) in Cohort B2 underwent truly serial OCT examinations at 3 different time points (Cohort B1: post-procedure, 6 months, and 2 years; B2: post-procedure, 1 year, and 3 years) after implantation of an 18-mm scaffold. A frame-by-frame OCT analysis was performed at the 5-mm proximal, 5-mm distal edge, and 2-mm in-scaffold margins, whereas the middle 14-mm in-scaffold segment was analyzed at 1-mm intervals. Results The in-scaffold mean luminal area significantly decreased from baseline to 6 months or 1 year (7.22 ± 1.24 mm2 vs. 6.05 ± 1.38 mm2 and 7.64 ± 1.19 mm2 vs. 5.72 ± 0.89 mm2, respectively; both p < 0.01), but remained unchanged from then onward. In Cohort B1, a significant increase in mean luminal area of the distal edge was observed (5.42 ± 1.81 mm2 vs. 5.58 ± 1.53 mm2; p < 0.01), whereas the mean luminal area of the proximal edge remained unchanged at 6 months. In Cohort B2, the mean luminal areas of the proximal and distal edges were significantly smaller than post-procedure measurements at 3 years. The mean luminal area loss at both edges was significantly less than the mean luminal area loss of the in-scaffold segment at both 6-month and 2-year follow-up in Cohort B1 or at 1 year and 3 years in Cohort B2. Conclusions This OCT-based serial EVR and SVR evaluation of the Absorb Bioresorbable Vascular Scaffold (Abbott Vascular, Santa Clara, California) showed less luminal loss at the edges than luminal loss within the scaffold. The luminal reduction of both edges is not a nosologic entity, but an EVR in continuity with the SVR, extending from the in-scaffold margin to both edges. (ABSORB Clinical Investigation, Cohort B [ABSORB B]; NCT00856856)