»Occlusion Myocardial Infarction« (OMI) - a new classification proposed to improve detection beyond strict STEMI criteria

The classification of acute myocardial infarction (AMI) based on ECG changes has evolved over time. Before the revascularization era, AMI was classified based on Q-waves that indicate loss of myocardium. After thrombolysis trials in the 1990s demonstrated a survival benefit, ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI) classifications were introduced to guide immediate reperfusion therapy with thrombolysis or percutaneous coronary intervention. However, STEMI criteria have limitations. ST elevation is not synonymous with acute coronary occlusion and can occur in pericarditis, early repolarization, left ventricular hypertrophy and other disorders. The process of occlusion is dynamic, and temporary thrombus resolution may cause ST elevation to be absent at the time of ECG recording. Furthermore, ST elevation depends on vector orientation; posterior infarcts may only show ST depression. Studies show that many NSTEMI cases are caused by acute occlusions, which are associated with worse prognosis. The sensitivity of current STEMI criteria is low, and several ECG findings suggestive of acute coronary occlusion have been described. A new classification, »Occlusion Myocardial Infarction« (OMI), has been proposed to improve detection and guide intervention beyond strict STEMI criteria.