INTRODUCTION: Ischemic mitral regurgitation (MR) is a widely recognized complication of coronary artery disease. The causes of ischemic MRs are presumably due to left ventricular (LV) dilatation or regional asynergy at the site of papillary muscles. Rarely, patients develop severe of MR after isolated surgical revascularization. The aim of this study was to evaluate the reasons why ischemic MR can become worse after surgical revascularization.METHODS: From 1985 to 1994, eighteen patients had worse MR after surgical revascularization. They were assessed for mitral annulus diameter, hemodynamics and LV regional wall motion by echocardiography and radioscopic ventriculography using the centerline technique.RESULTS: No Q waves appeared on electrocardiography. Hemodynamic studies were as follows: pulmonary artery wedge pressure (preMR vs. post MR: 12.2 +/- 6.4 (mean +/- SD) vs. 16.7 +/- 9.5 mmHg, P < 0.05), end diastolic volume index (99.5 +/- 34.4 vs. 106.0 +/- 34.8 ml/m 2 , ns), ejection fraction (47.7 +/- 11.9 vs. 43.2 +/- 14.5%, ns), cardiac index (3.50 +/- 1.06 vs. 3.51 +/- 1.12 l/min/m 2 , ns). Regional wall motion showed that the diaphragmatic, postero-basal and posterolateral segments correlate with the severity of MR(P < 0.05). Mitral annulus diameter correlates with the severity of MR(P < 0.05).DISCUSSION: It is presumed that the significant increase in pulmonary artery wedge pressure reflects the appearance of MR. In this study, we found that the causes of ischemic MR after surgical revascularization are regional asynergy at the site of papillary muscles, and mitral annulus dilatation not depending on left ventricular volume. Our findings suggest that ischemic heart disease with large mitral annulus needs total revascularization and mitral annuloplasty.