Myocardial Infarction With Non-obstructive Coronary Arteries (MINOCA) Revealing Coronary Embolism From Left Atrial Appendage Thrombus in Rheumatic Valvular Atrial Fibrillation.

Myocardial infarction with non-obstructive coronary arteries (MINOCA) represents a diagnostic challenge with multiple underlying mechanisms, including coronary embolism. We report the case of a 50-year-old woman with a history of rheumatic fever who was admitted for acute chest pain. Electrocardiography showed atrial fibrillation with inferolateral ischemic changes, and elevated troponin levels confirmed myocardial infarction. Transthoracic echocardiography revealed moderate mitral stenosis, severe aortic stenosis, and left atrial enlargement. Coronary angiography demonstrated thrombotic occlusion of the second obtuse marginal branch without significant atherosclerotic disease. Transesophageal echocardiography identified a left atrial appendage thrombus, supporting a cardioembolic mechanism. This case emphasizes the importance of considering coronary embolism in MINOCA, particularly in patients with valvular atrial fibrillation, and highlights the role of a structured diagnostic approach in guiding diagnosis and management.