Prognostic significance of type 4a myocardial infarction and periprocedural myocardial injury in NSTEMI patients

Abstract Background Type 4a myocardial infarction (MI) and periprocedural myocardial injury (PMI) might occur in patients with non-ST-elevation MI (NSTEMI) after percutaneous coronary intervention (PCI) procedures. Purpose This study investigated the incidence and prognostic relevance of type 4a MI and PMI, according to current definitions, in NSTEMI patients undergoing PCI. The best cardiac troponin (cTn) threshold of PMI for prognostic stratification is also identified. Methods In this observational cohort study, we enrolled consecutive NSTEMI patients undergoing PCI with stable or falling pre-PCI cTn levels. According to the 4th Universal Definition of Myocardial Infarction (UDMI), we stratified the study population into three subgroups: those experiencing 1) type 4a MI; 2) PMI; 3) no periprocedural ischemic events. The primary endpoint was 1-year all-cause mortality. The secondary endpoint consisted in a composite of major adverse cardiovascular events (MACE) at 1-year, including all-cause mortality, non-fatal reinfarction, urgent revascularization, non-fatal ischemic stroke and hospitalization for heart failure. Results Among 1412 NSTEMI patients undergoing PCI with stable or falling cTn levels at baseline, 240 (17.0%) experienced type 4a MI, 288 (20.4%) PMI, and 884 (62.6%) no periprocedural ischemic events. Patients with type 4a MI had the highest 1-year all-cause mortality and MACE rates. PMI defined by the 4th UDMI (post-PCI delta cTn >20%) did not show significant associations with primary and secondary endpoints. PMI redefined as post-PCI delta cTn >40% was significantly correlated with 1-year all-cause mortality and MACE. Conclusion Periprocedural ischemic events are common in NSTEMI patients undergoing PCI and influence patient outcomes. Type 4a MI and PMI redefined as post-PCI delta cTn >40% are strongly associated with 1-year death and MACE. This study highlights the importance of identifying periprocedural ischemic events to aid risk stratification and management of NSTEMI patients.PMI and type 4a MI: mortality 1-yearPMI and type 4a MI: MACE 1-year