Background: It has been reported that timely corrective surgery does not improve exercise capacity in a substantial number of patients with chronic severe MR. We sought to determine preoperative predictors for postoperative improvement of exercise capacity in chronic MR.
Methods: 26 patients with pure severe MR undergoing mitral valve surgery were prospectively enrolled.Cardiopulmonary function test and EchoCG were performed at baseline and 6 months after surgery (Among 32 patients, 7 patients who did not maximal exercise were excluded) Results: At baseline, mean end-diastolic and end-systolic left ventricular volume indexes are 119±25, 44±12ml/m2, respectively. LV ejection fraction(EF) was 62±6%, and regurgitant fraction(RF) 70±10cm2. In all, maximal oxygen consumption (VO2 max) did not improve after surgery (22.3±6.5 vs 22.3±6.6 ml/kg/min,p=NS). When we compared various echocardiographic parameters between patients with (Group 1,n=10) and without (Group 2, n = 16) improvement of exercise capacity (> 10% increase of VO2 max), there were no significant differences in age, EF( 60±6.1 vs 64±6.3, P=NS),RF,pulmonary artery pressure, and LVEDV & LVESV index.Averaged (septal & lateral) peak systolic velocity of mitral annulus (S’) (8.11±1.59 vs 5.91±1.15cm/s, p=0.001),averaged longitudinal myocardial strain rate (-1.01±0.20 vs -0.75±0.06 S-1 p<0.0001) and averaged (mid septal and posterior wall) radial strain rate (1.28±10.51 vs 0.88± 0.30S-1 p=0.02) were significantly higher in Group 1. In addition, group 1 showed lower systolic synchroniciry index (23.9±5.33 vs 36.30±9.46 ms, p=0.013). ΔVO2max (postoperative - preoperative VO2max) was well correlated with S'velocity (R= 0.489, p=0.01).In ROC curve analysis, S’velocity>6cm/s showed good sensitivity (100%) and specificity (72%) for predicting the improvement of exercise capacity after surgery(AUC=0.844).
Conclusion: It seems that the absence of subclinical LV systolic dysfunction (high systolic annulus velocity, high systolic myocardial strain rate, low systolic synchronicity index) in patients with preserved systolic function is a good predictor for postoperative improvement of exercise capacity in chronic MR.
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