Acute myocardial infarction with normal and near normal coronary arteries. Documentation with coronary arteriography within 12 1/2 hours of the onset of symptoms in two cases (three episodes).

Three instances (in two patients) of acute myocardial infarction associated with arteriographically normal or near normal coronary arteries are reported. One patient with a lateral infarction had a normal coronary arteriogram and hypokinesia of the lateral wall. Another patient had two infarctions: (1) a transmural inferior-lateral infarction associated with occlusion of the most distal segment of the posterior descending branch of the right coronary artery, and (2) a transmural anterior-lateral-superior infarction associated with occlusion of the most distal segment of the left anterior descending coronary artery. Neither occlusion was consistent with the extent of infarction. Although coronary arteriography was performed as early as 12 1/2, 3 3/4 and 11 2/3 hours, respectively, after the onset of symptoms of infarction in these three instances, the pathophysiologic features of the infarctions are obscure. Temporary occlusion of an epicardial coronary artery by spasm or platelet aggregates, or both, is suggested as a possible mechanism of the acute event.