What the electrocardiogram is being asked to detect in acute myocardial infarction: The case for the OMI/NOMI paradigm.

The electrocardiogram is the pivotal triage instrument in suspected acute myocardial infarction, yet for three decades its interpretation has been reduced to a single feature: whether ST-segment elevation meets a fixed millimeter threshold. Approximately one-quarter to one-third of patients labeled non-ST-segment elevation myocardial infarction (NSTEMI) harbor total culprit artery occlusion at next-day angiography, sustain infarct sizes and mortality comparable to or worse than ST-segment elevation myocardial infarction (STEMI), and are younger and less comorbid - indicating that adverse outcomes reflect delayed reperfusion rather than baseline risk. The occlusion myocardial infarction versus non-occlusion myocardial infarction (OMI/NOMI) framework reorients electrocardiographic interpretation around acute coronary occlusion rather than a single morphological criterion. This review examines the principal arguments advanced in defense of the ST-elevation-only reading standard as electrocardiographic propositions: what the electrocardiogram is being asked to detect, what it predicts when read for occlusion, how its interpretation shapes the timing and selection of reperfusion, and whether an expanded reading standard can be operationalized without loss of diagnostic performance. The evidence shows that the call for dedicated randomized trials misunderstands a purely diagnostic paradigm, that early-invasive trials in NSTEMI were neither early nor selective, that fibrinolytic benefit in non-ST-elevation occlusion was obscured by heterogeneous pooling, and that expanded interpretation - increasingly scalable through artificial intelligence - improves sensitivity and specificity simultaneously. The electrocardiogram has not failed; the reading standard applied to it has.