Clinical significance of mitral regurgitation in patients with recent myocardial infarction

The prognostic implications of the presence of mitral regurgitation (MR) in patients with recent myocardial infarction has not been clarified yet. In March 1983, we undertook a prospective study in patients surviving a first episode of acute myocardial infarction. Over a 4-year period, 266 patients entered the study. Left ventriculography documented the presence of MR in 51 patients, while 215 did not have angiographic evidence of MR. The presence of MR was associated with larger infarcts, as shown by greater values of peak CK( P < 0·05) and by the prevalence of Q-wave vs non-Q-wave infarctions ( P < 0·05). Transient left ventricular failure during hospitalization was more frequent in patients with MR ( P < 0·05), while the occurrence of early post-infarction angina was similar in the two groups of patients. No difference was found in the extent of coronary disease, yet patients with MR had higher values of left ventricular end diastolic pressure (LVEDP) ( P < 0·005) and a lower ejection fraction (EF) ( P < 0·001). Patients with MR had a reduced exercise capacity ( P < 0·005), but signs of myocardial ischaemia were similarly distributed in the two groups. Patients with anterior infarcts and MR had higher left ventricular volumes than patients without MR, while no difference was found between patients with and patients without MR and inferior infarction, suggesting that left ventricular dilatation may play an important role in the pathogenesis of MR in patients with anterior but not in those with inferior infarction. After a mean follow-up period of 15 months, patients with MR were more frequently in NYHA class II or III( P < 0·001) and had a lower survival rate than patients without MR ( P < 0·05). We conclude that MR is found in about 20% of patients with a recent single episode of myocardial infarction. Its presence is associated with larger infarcts, with a more pronounced impairment of left ventricular function and with a worse long-term prognosis.