An Evaluation of Left Ventricular Function after Surgery for Pure Mitral Regurgitation Using Dobutamine-stress Echocardiography. Should the Mitral Complex Be Preserved?

Abstract

Summary: To evaluate the importance of preserving the mitral complex, clinical outcomes and postoperative left ventricular (LV) functions of 175 patients with pure mitral regurgitation (MR) were analyzed. They were divided into three groups; patients who had conventional mitral valve replacement (cMVR; n=47), posterior mitral leaflet preserved MVR (pMVR; n=66) or mitral valvuloplasty (MVP; n=62). There was no operative death or hospital death in this study. The actuarial survival rate was 85.2% in cMVR, 78.5% in pMVR, and 84.7% in MVP at 10 years after operation. The actuarial freedom from reoperation 10 years postoperatively was 100% in cMVR, 97.9% in pMVR, 85.8% in MVP. The actuarial freedom from thromboembolism (TE) at 10 years was 92.2% in cMVR, 87.1% in pMVR, 93.5% in MVP. Freedom from all types of events including non-cardiac death was 78.3% in cMVR, 64.8% in pMVR, 65.3% in MVP at 10 years, respectively. Pre-and postoperative LV function was evaluated using echocardiography. Patients with MVP had better LV performance than those with MVR. However, there was no significant difference between the cMVR and pMVR groups. For further estimation of postoperative LV function, dobutaminestress echocardiography (DSE) was performed. The results of DSE revealed that the LV contractility in MVP was obviously better than those in MVR groups especially in systole. The change in ejection fraction (EF) from baseline to peak dobutamine stress in the pMVR group was significantly greater than in cMVR. This study supports the concept that the preservation of continuity between the mitral annulus and papillary muscle plays an important role in clinical outcome and postoperative LV function. In conclusion, MVP should be a first choice as an operative method for pure MR when technically feasible. When it is impossible to perform MVP, pMVR, not cMVR, should be the next choice. This study suggests that preservation of papillary muscle-mitral annular continuity during mitral valve surgery for pure MR is beneficial to LV systolic function.