Predictors of reduction in mitral regurgitation in patients undergoing cardiac resynchronisation treatment

Background: CRT causes reduction in MR due to left ventricular (LV) remodelling, but determinants of clinically meaningful MR reduction acutely after CRT have not been evaluated. Objectives: We evaluated echocardiographic predictors of significant reduction in functional mitral regurgitation (MR) by cardiac resynchronisation treatment (CRT). Methods: 35 patients with ≥ moderate to severe MR underwent CRT for presence of electrical and/or mechanical dyssynchrony. Significant reduction in MR post-CRT was defined as reduction to less than moderate MR (MR jet area/left atrial area <25%, group 1) on follow-up echocardiogram at 1.7 (SD 2.8) months post-CRT. Results: Significant MR reduction of 62% (28%) from baseline MR occurred in 18 patients vs 22% (16%) in the remaining patients (group 2), p<0.01). Follow-up left ventricular ejection fraction (LVEF) was 0.43 (0.09) in group 1 patients vs 0.29% (0.1%) in group 2 patients (p<0.001). On multivariate analysis, time to peak strain in the mid inferior segment was the only significant predictor of MR reduction post-CRT (p = 0.008, OR = 1.023 (CI 1.006 to 1.041). The sensitivity and specificity of the combined variable of time to peak strain of >400 ms in the mid inferior segment and peak negative strain of ≥9% and 8% in the basal and mid posterior segments, respectively, to predict follow-up MR was 88% and 93% respectively and positive and negative predictive value was 94% and 87%. Conclusion: In patients with cardiomyopathy and significant MR, the presence of delayed longitudinal strain in the mid inferior LV segment along with preserved negative systolic strain in the basal and mid posterior segments predicts substantial reduction in MR post-CRT.