Temporal Changes of Left Ventricular Contractile Function after Corrective Surgery in Mitral Regurgitation: Difference according to the Type of Surgery and Its Clinical Significance

ABSTRACT

BACKGROUND AND OBJECTIVES: Although it is well known that postoperative left ventricular contractile function is an important prognostic factor in mitral regurgitation, temporal changes of left ventricular contractile function could not be evaluated due to lack of follow-up studies and the difference according to the type of surgery was not established. We addressed these issues by analyzing the data of serial echocardiographic studies and sought to determine factors associated with mortality and cardiovascular events during follow-up. MATERIALS AND METHOD: Retrospective analysis of echocardiographic data and medical records was done in patients who underwent corrective surgery for significant mitral regurgitation at the Asan Medical Center from January 1990 to December 1997. Patients who underwent echocardiography before and immediately after the surgery, and follow-up study at least 6 months later were selected for the analysis. RESULTS: Of 199 patients who underwent mitral valve surgery for mitral regurgitation during that period, 164 patients were included in this study. Among them, 89 patients underwent valve repair and 75 valve replacement. Immediately after surgery, ejection fraction decreased significantly in all patients (62+/-9% vs. 50+/-10%, p<0.01). At the average of 32 months after surgery, ejection fraction was significantly higher in the repair group than in the replacement group (57+/-10% vs. 52+/-11%, p=0.01). During follow-up (mean 32+/-24 months), there were 53 cardiovascular events in 33 patients (heart failure in 14, cardiac death in 11, stroke in 11, reoperation in 11, hemorrhage in 4, thromboembolism in 1 and endocarditis in 1). Cardiovascular events were significantly more frequent in valve replacement group than in valve repair group (23/75 vs. 10/89, p=0.002). Multivariate analysis showed that the independent predictors of all cardiovascular events were immediate postoperative end-systolic volume (p=0.006, hazard risk=1.026, 95% CI=1.01~1.05) and age (p=0.04, hazard risk=1.07, 95% CI=1.001-1.14). The overall survival rate was 85+/-6% at 7 years. Multivariate analysis revealed an independent beneficial effect of valve repair on overall survival (p=0.0058, hazard ratio=0.046, 95% CI=0.005-0.411). CONCLUSION: After surgery, ejection fraction decreased significantly in both groups. However, patients with repair showed progressive improvement of left ventricular contractility and revealed higher ejection fraction at the follow-up study than those with replacement, which might contribute to higher survival rate in this group.