Acute myocardial-infarction-like findings with myocarditis in infancy. A case report.

A four-and-a-half-month-old infant suffered sudden circulatory collapse early in the course of a brief febrile illness. The electrocardiogram initially appeared normal; an abrupt change indicative of extensive myocardial infarction occurred following stabilization. Coronary arterial anatomy and flow by echocardiography and angiography were normal except for the finding of single origin of the entire coronary system from the left sinus of Valsalva. Gallium 67 myocardial imaging was positive for an inflammatory process, and the diagnosis of myocarditis was supported. This is the first case, to the authors' knowledge, of myocarditis simulating myocardial ischemia in an infant of an age in which anomalous origin of the left coronary artery from the pulmonary artery is a recognized cause for myocardial infarction.