Early Improvement in Mitral Regurgitation after Cardiac Resynchronization Therapy in Cardiomyopathy Patients.

BACKGROUND: The study aim was to investigate factors affecting the improvement of mitral regurgitation (MR) severity within 48 hours after cardiac resynchronization therapy (CRT) in patients with cardiomyopathy. METHODS: Sixty-nine cardiomyopathy patients (48 males, 21 females; mean age 59.12 ± 9.66 years) in NYHA functional class ≥III, with left ventricular ejection fraction (LVEF) ≤35%, and QRS duration >120 ms, with MR ≥moderate, were included in the study. Conventional echocardiography was performed before and within 48 h after CRT, and all patients underwent tissue Doppler imaging prior to CRT. Improved MR was defined as a reduction of at least one grade in MR severity. RESULTS: After CRT, 49 patients (71%) showed MR improvement but 20 (29%) had no MR improvement. The mean MR severity grade was reduced significantly, from 2.70 ± 0.77 before CRT to 1.90 ± 0.94 after CRT (p<0.001). The group with improved MR had a significantly higher rate of left bundle branch block (75.5% versus 45%; p = 0.015), a higher QRS duration (172.00 ± 31.98 versus 147.25 ± 28.75 ms; p = 0.001), a higher median septal lateral delay (70 versus 35 ms, p = 0.035), and a higher median anteroseptal to posterior-wall delay by M mode (200 versus 130 ms, p = 0.041). Older age, longer QRS duration, and septallateral delay remained significant independent predictors of MR improvement. A greater proportion of patients with improved MR showed ≥5% increase in LVEF (55.1% versus 30.0%, p = 0.058). CONCLUSIONS: CRT acutely reduced the severity of functional MR in the majority of cardiomyopathy patients. Those patients with improved MR showed a higher frequency of ≥5% increase in LVEF after CRT. Older age, longer QRS duration, and septallateral delay were independent predictors of MR improvement after CRT.