Subendocardial infarction in retrospect: pathologic, cardiographic, and ancillary features.

Fifty-three patients with subendocardial infarction (SEMI) were studied at autopsy; all were elderly and the group was equally divided by sex. About half had more than one SEMI; the recurrences or extensions often involved superjacent, but not infrequently adjacent, areas. Six showed fibrinous pericarditis. This larger study showed more widespread and severe coronary narrowing than an earlier report. Six patients had thrombi in the right coronary artery. Six showed electrocardiographic evidence of concomitant anteroseptal and inferior (Roesler-Dressler) infarction, and 12 had intraventricular block generally preceding higher-grade block or arrhythmias. At some time during their terminal hospitalization, 27 patients, or half, developed distinctive protracted RS-T depression or T wave inversion. Twenty-four of the SEMIs were diagnosed on accepted criteria as transmural infarct; that diagnosis was sustained in only four. Thus neither the presence of changes in RS-T segment or T wave nor the absence of QRS changes are mandatory for the diagnosis of SEMI; this invalidates the common assumption that the diagnosis is not justified unless these conditions are met.