Prognostic significance of mitral regurgitation in acute myocardial infarction

To define the frequency, natural history and clinical correlates of the murmur of mitral regurgitation (MR) detected after myocardial infarction, clinical data from 849 patients with documented acute myocardial infarction were analyzed. A murmur suggestive of MR was present on admission in 76 patients (9%). Patients with MR on admission were older and more apt to be female and nonwhite. They also had a significantly greater frequency of prior infarction and signs and symptoms of congestive heart failure. There was no difference in the location (anterior or inferior) of infarction. Patients with MR on admission had a 36% mortality compared to 16% for those who developed MR later in the hospitalization and 15% for those without MR by auscultation (p < 0.001). Correction for diferences in baseline variables indicated that the presence of MR on admission did not contribute independently to mortality. Thus, the murmur of MR derives its prognostic significance from integration of multiple clinical, radiographic and electrocardiographic characteristics.