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

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.

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.

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).

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.