Characteristics, Predictors, and Mechanisms of Thrombosis in Coronary Bioresorbable Scaffolds

Objectives The study sought to investigate the incidence, characteristics, predictors, and possible mechanisms of early and 3-year coronary scaffold thrombosis (ScT). Background An increased incidence of both early and late ScT has been shown in randomized trials. Methods Consecutive patients were enrolled in a single-center registry. Quantitative coronary angiography was performed. Incidence and predictors of ScT were assessed with Kaplan-Meier and Cox regression analyses. Results A total of 657 patients (63 ± 12 years of age, 79% men, 21% diabetic, 64% acute coronary syndrome) who received 925 coronary bioresorbable scaffolds (BRS) (Abbott Vascular, Santa Clara, California) between May 2012 and January 2015 were enrolled. Clinical and procedural characteristics and outcome data at 1,076 (interquartile range: 762 to 1,206) days (3-year follow-up rate 93%) were collected. Twenty-eight ScTs were recorded: 14 early (Kaplan-Meier estimate: 2.2%), 5 late (Kaplan-Meier estimate: 0.9%), and 9 very late (Kaplan-Meier estimate: 1.7%). The incidence of ScT followed a U-shaped curve with highest incidence at the extremes of the distributions of reference vessel diameter (RVD) and the ratio of BRS nominal diameter to RVD. At quantitative coronary angiography, RVD (hazard ratio [HR]: 0.14; 95% confidence interval [CI]: 0.04 to 0.49) and BRS oversizing (ratio of BRS nominal diameter to RVD >1.15; HR: 107.40; 95% CI: 9.20 to 1,261.30) emerged as potent predictors of early ScT. RVD (HR: 9.55; 95% CI: 3.90 to 23.42) and BRS undersizing (ratio of BRS nominal diameter to RVD Conclusions Different mechanisms underlie early and late ScT: although incomplete BRS deployment was a predictor of the former, the latter was associated with large vessel size and BRS undersizing. However, both phenomena are significantly less frequent with an optimized implantation technique. (Mainz Intracoronary Database. The Coronary Slow-flow and Microvascular Diseases Registry [MICAT]; NCT02180178)