Third universal definition of myocardial infarction: update, caveats, differential diagnoses.

Updated definitions of myocardial infarction (MI) reflect research on measuring cardiac troponin to diagnose MI. Elevations of this biomarker indicate cardiac injury but not always an acute coronary syndrome. Clinical judgment is needed to interpret increasingly sensitive biomarker assays appropriately. Here, we review the new MI definitions and the various causes of elevated troponin to enable physicians to differentiate acute coronary syndromes from other conditions.