Echocardiographic prediction of survival after surgical correction of organic mitral regurgitation

Background: Left ventricular dysfunction is a frequent cause of death after successful surgical repair of mitral regurgitation. The role of preoperative echocardiographic left ventricular variables in the prediction of postoperative survival and thus their clinical implications remain uncertain. Methods and Results: The survival of 409 patients operated on between 1980 and 1989 for pure, isolated, organic mitral regurgitation and with a preoperative echocardiogram (within 6 months of operation) was analyzed. The overall survival was 75% at 5 years (90% of expected), 58% at 10 years (88% of expected), and 44% at 12 years (73% of expected). Operative mortality was 6.6% and markedly improved from 1980 to 1984 (10.7%) to 1985 to 1989 (3.7%). Multivariate analysis showed that age (P=.0003), date of operation (P=.003), and functional class (P=.016) but not left ventricular function were predictors of operative mortality. In the most recent period (1985 to 1989), operative mortality was 12.3% in patients age 75 years or older and 1.1% in patients younger than 75 years. Late survival was analyzed in the operative survivors. Multivariate analysis showed that the most powerful predictor was echocardiographic ejection fraction (EF) (P=.0004), followed by age (P=.0031), creatinine level (P=.0062), systolic blood pressure (P=.0164), and presence of coronary artery disease (P=.0237). The late survival at 10 years was 32±12% for patients with EF <50%, 53±9% for EF 50% to 60%, and 72±4% for EF ≥60%. The hazard ratio compared with EF ≥60% was 2.79 (95% confidence interval, 1.65 to 4.72) for EF <50% and 1.81 (95% confidence interval, 1.11 to 2.95) for EF 50% to 60%. Echocardiographic EF remained the best predictor of late survival, even when combined with left ventricular angiographic variables. The survival of patients with EF ≥60% was 100% of expected at 10 years but was better in patients in class I or II than in those in class III or IV (82±6% versus 59±6%, respectively, at 10 years; P=.0021). The preoperative predictors of operative and late mortality remained significant independent of the type of surgical correction performed in combined multivariate analyses. Conclusions: In organic mitral regurgitation, (1) operative mortality has markedly decreased recently, being at a low 1.1% in patients younger than 75 years, and is predicted by age and symptoms and not by left ventricular function, and (2) left ventricular EF measured by echocardiography is the most powerful predictor of late survival. These results suggest that surgical treatment should be considered early, even in the absence of severe symptoms, in patients with severe mitral regurgitation, before left ventricular dysfunction occurs.