The "papillary muscle dysfunction" concept includes a disrupted sequence of one or more structures of the mitral valve complex and not merely a disturbance of a papillary muscle itself. We studied a group of seventeen patients, 14 men and 3 women (mean age 51 and 39 years, respectively). Acute myocardial infarction was the first evidence of heart disease. In all of them, Doppler and M mode echocardiography were performed and correlation clinical features were done. In addition a tricuspid regurgitation flow patterns was scanned on each patient. Mitral regurgitation was found in 29% of them by Doppler echocardiography and only 17% had a mitral systolic murmur suggestive of this entity. In those patients with mitral regurgitation-flow patterns, the infarct site was similar to those with anterior and inferior infarction and serum CPK-level was greater in these patients than the non-mitral regurgitation flow pattern group. The evidence of tricuspid regurgitation by pulsed-Doppler echocardiography was associated with mitral regurgitation in 80% of patients, mainly those with right ventricular extension of acute myocardial infarction, and with the greatest hemodynamic impairment. It seems likely in this study, that mitral regurgitation was due to valve ring dilation with an increase of left ventricular diameter and a decrease on ventricular systolic function.