BACKGROUND - Numerous definitions for peri-procedural myocardial infarction (PMI) following percutaneous coronary intervention (PCI) and coronary bypass grafting (CABG) surgery exist.

OBJECTIVES - The purpose of this study was to investigate the PMI rates according to various definitions, their clinically relevant association with all-cause mortality at 10 years, and their impact on composite endpoints at 5 years in the SYNTAXES (Synergy between PCI with Taxus and Cardiac Surgery Extended Survival) trial.

METHODS - PMI was classified as a myocardial infarction occurring within 48 h of the procedure according to definitions of the SYNTAX (TAXUS Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries), ISCHEMIA (International Study Of Comparative Health Effectiveness With Medical And Invasive Approaches), and EXCEL (Evaluation of XIENCE versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization) trials; the Fourth Universal Definition of MI; and the Society for Cardiovascular Angiography and Interventions (SCAI). Of the 1,800 patients enrolled, 1,652 with creatine kinase and/or creatine kinase-myocardial band (CK-MB) post-procedure were included. The association between PMI and mortality was analyzed by Cox regression.

RESULTS - PMI rates according to the SYNTAX and Fourth Universal Definition of MI, both of which required CK-MB elevation and electrocardiographic evidence of permanent myocardial damage, were 2.7% and 3.0%, respectively, in the PCI arm versus 2.4% and 2.1%, respectively, in the CABG arm. PMI rates according to the SCAI or EXCEL definition were higher in the PCI (5.7%) and CABG (16.5%) arms. PMIs according to the SYNTAX and Fourth Universal Definition of MI were more strongly associated with mortality than EXCEL and SCAI PMIs defined by isolated enzyme elevation when CK-MB was more than 10 times ULN. The impact of these “enzyme-driven events” on time-to-event curves and the composite endpoints was greater in the surgical cohort. PMIs after PCI were associated with 10-year mortality regardless of definition, whereas their impact on mortality after CABG was limited to 1 year.

CONCLUSIONS - The rates of PMI are highly dependent on their definition, which affects time-to-event curves, composite endpoints, and their lethal prognostic relevance. (Synergy Between PCI With TAXUS and Cardiac Surgery: SYNTAX Extended Survival [SYNTAXES]; NCT03417050; SYNTAX Study: TAXUS Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries [SYNTAX]; NCT00114972)