Inferolateral ST-Segment Elevation Myocardial Infarction Secondary to Suspected Coronary Embolism in a Patient with Paroxysmal Atrial Fibrillation: A Case Report

Coronary embolism is an underrecognized nonatherosclerotic cause of ST-segment elevation myocardial infarction (STEMI), most commonly associated with atrial fibrillation. We report a 76-year-old man with paroxysmal atrial fibrillation who presented with acute substernal chest pain and inferolateral STEMI. Coronary angiography demonstrated a 100% thrombotic occlusion of the distal right posterolateral ventricular branch with otherwise nonobstructive coronary artery disease. In the setting of an abrupt distal coronary occlusion, minimal underlying atherosclerotic disease, paroxysmal atrial fibrillation, and fulfillment of the Shibata diagnostic criteria, coronary embolism was considered the most likely mechanism. Long-term anticoagulation was continued, and the patient remained asymptomatic at 1-month follow-up. This case highlights the diagnostic challenge of suspected coronary embolism in patients presenting with STEMI, atrial fibrillation, and minimal underlying coronary artery disease.