OBJECTIVES This study sought to evaluate the mechanism of post-procedural cardiac biomarker (CB) rise following device implantation. BACKGROUND A fully bioresorbable Absorb scaffold, compared with everolimus-eluting metallic stents (EES), might be associated with a higher incidence of periprocedural myocardial injury. METHODS In 501 patients with stable or unstable angina randomized to either Absorb (335 patients) or EES (n = 166) in the ABSORB II trial, 3 types of CB (creatine kinase, creatine kinase-myocardial band, and troponin) were obtained before and after procedure. Per protocol, periprocedural myocardial infarction (PMI) was defined as creatine kinase rise >2x the upper limit of normal with creatine kinase-myocardial band rise. RESULTS Incidence of side branch occlusion and any anatomic complications assessed by angiography was similar between the 2 treatment arms (side branch occlusion: Absorb: 5.3% vs. Xience: 7.6%, p = 0.07; any anatomic complication: Absorb: 16.4% vs. EES: 19.9%, p = 0.39). Fourteen patients who presented with recent myocardial infarction at entry with normalized creatine kinase-myocardial band according to the protocol were excluded for post-CB analysis. The overall compliance for CB was 97.8%. The CB rise subcategorized in 7 different ranges was comparable between the 2 treatment arms. PMI rate was numerically higher in the Absorb arm according to the per-protocol definitions, and treatment with overlapping devices was the only independent determinant of per-protocol PMI (odds ratio: 5.07, 95% confidence interval: 1.78 to 14.41, p = 0.002). CONCLUSIONS There were no differences in the incidence of CB rise and PMI between Absorb and EES. Device overlap might be a precipitating factor of myocardial injury. (ABSORB II Randomized Clinical Trial: A Clinical Evaluation to Compare the Safety, Efficacy, and Performance of Absorb Everolimus Eluting Bioresorbable Vascular Scaffold System Against Xience Everolimus Eluting Coronary Stent System in the Treatment of Subjects With Ischemic Heart Disease Caused by De Novo Native Coronary Artery Lesions [ABSORB II]; NCT01425281). (C) 2015 by the American College of Cardiology Foundation.