Anatomic findings in acute papillary muscle necrosis.

To investigate the consequences of acute papillary muscle necrosis of the left ventricle, 25 cases from a total of 133 autopsies of acute myocardial infarction were studied. Cardiac hypertrophy was found in 84%. The anterior papillary muscle was involved in four cases, the posterior in 13, and both muscles in eight. Left ventricular subendocardial infarction was found in 32% of cases. The size of left ventricular necrosis ranged from 11% to 75% of the left ventricular mass. Associated right ventricular infarction was observed in 68%. There were 19 cases of cardiogenic shock, four cases of pulmonary edema, and two cases of sudden death. We conclude that papillary muscle necrosis is usually associated with cardiac hypertrophy, posterior necrosis of both ventricles, and subendocardial infarction. Acute mitral regurgitation is probably an important contributing factor to clinical impairment and death, mostly in cases of small necrosis.