LAUSR

BACKGROUND Functional mitral regurgitation(FMR) in patients with cardiomyopathy correlates with morbidity and mortality in heart failure. The response of FMR to cardiac resynchronization therapy(CRT) varies. OBJECTIVES The aim of our study was to analyze the incidence and severity of FMR in patients with non-ischemic cardiomyopathy(NICM) and left bundle branch block(LBBB) and the response to left bundle branch pacing(LBBP). METHODS Patients who had undergone LBBP for NICM, LBBB and FMR between 2019 to 2021 were included retrospectively in the study. RESULTS A total of 79-patients were identified and six patients excluded(5-no consistent LBB-capture and 1-prosthetic-mitral valve). Patients(n=73) were divided into two groups based on the severity of FMR- Group-I(mild FMR)(n=35;48%) and Group-II(significant FMR)(n=38;52%). The mean follow-up duration was comparable in both groups. Group-II was characterized by higher NT-pro BNP levels, NYHA-function class and larger left-ventricular dimensions. LBBP resulted in significant reduction in QRS duration in both group-I(113.8±12.7ms;p<0.0001) and group-II(117.3±10.3ms;p <0.0001). LBBP resulted in similar percentage reduction in QRS duration(-31±10% vs -33±8%;p = 0.34), LVEDD(-8±10% vs -11±12%;p= 0.25), LVEDV(-26±12% vs -31±27%;p= 0.31) and LVESV(-39±16% vs -37±30%;p= 0.72) in group-I and group-II respectively. The percentage change(+59±39% vs +59±41%;p-1.0) and absolute change(+19.9±10.4% vs +17±10.04%;p-0.22) in LVEF were similar in both the groups. In group-II, 31-patients (82%) showed significant reduction in FMR-severity during follow-up. No patients in group-I showed worsening of FMR. CONCLUSION LBBP resulted in excellent electrical resynchronization with significant reduction in the severity of FMR in the majority of patients with significant FMR and no worsening of FMR from baseline in any patient.