Beyond Types 1–5: The Fifth Universal Definition of Myocardial Infarction

ACUTE myocardial infarction (MI) reflects acute myocardial injury, occurring in a setting of myocardial ischaemia, supported by symptoms, ischaemic ECG changes, new loss of viable myocardium on imaging, and/or coronary thrombus.1The Fifth Universal Definition of Myocardial Infarction (UDMI), developed jointly by the four major cardiac societies: the European Society of Cardiology (ESC), the American College of Cardiology (ACC), the American Heart Association (AHA), and the World Heart Federation (WHF), published 8 years from the last update,1 introduces a revised clinical classification of MI based on pathophysiology, clinical assessment, and objective diagnostic criteria.In this article, the authors review key changes, the underlying rationales, and implications for the practising clinician.