A generation ago the ST-elevation myocardial infarction (STEMI) paradigm led to quality improvement (QI) in the emergency department (ED). Now, insights from angiography and advances in electrocardiogram (ECG) interpretation have led to the new paradigm of occlusion myocardial infarction (OMI), creating the possibility of further QI. This article reviews the current STEMI paradigm, the emergence of the OMI paradigm, and the use of QI to continuously improve care for acute myocardial infarction (AMI) patients in the ED.