We have recently encountered a patient presenting an sudden cardiac death secondary to acute myocardial infarction as a complication of fibromuscular dysplasia (FMD) involving the coronary artery. A 30 years old woman, who had a 6 year history of hyperthyroidism, was carried to our hospital because of sudden cardiac arrest. With no vital signs at arrival, advanced life support make her heart beat and gave a stable hemodynamic condition, which allowed us to make a diagnosis of acute broad anterior myocardial infarction with electrocardiography, echocardiography and serum CK-MB isoenzyme. Her brain activity did not recovered. She died on day 6 of hospitalization. Postmortem examination confirmed a broad anterior wall infarction of a histologic age of several days. Histologic examination also revealed intimal fibrous thickening with an increase of smooth muscle cells and elastic fibers in the right coronary and the anterior descending branch of the left coronary arteries, as well as the vertebral, bronchial, intra-renal and superior mesenteric arteries. Whereas no complete obstruction in the coronary artery was found at autopsy, it seems likely that the intracoronary luminal narrowing induced by fibromuscular hyperplasia might have precipitated a myocardial ischemic insult which caused the sudden cardiac death. Although FMD of the coronary artery has been rare in literature, it is necessary to consider FMD in the differential diagnosis of identifiable causes of sudden death, particularly in the young generation
