Repercussion of functional mitral regurgitation on reverse remodelling in cardiac resynchronization therapy.

AIMS: Cardiac resynchronization therapy (CRT) reduces the degree of functional mitral regurgitation (FMR). However, FMR has also been associated with a lack of clinical response to CRT. We undertook this study to determine whether the presence of FMR influences the reverse remodelling induced by CRT. METHODS AND RESULTS: We used Doppler echocardiography to assess 20 patients with dilated cardiomyopathy before and 6 months after undergoing CRT. We evaluated the effect of reverse remodelling (reduction > or = 10% in end-systolic volume) according to the presence or absence of important FMR, defined as a regurgitant orifice area (ROA) of > or = 0.20 cm(2). Of the 20 patients (mean age, 64.7 +/- 8.2 years, eight women), 9 had marked FMR (ROA 0.40 +/- 0.12 cm(2)), 6 mild FMR (ROA 0.15 +/- 0.02 cm(2)), and 5 had trivial or no FMR. CRT reduced the presence of mitral regurgitation by 33.3% and induced reverse remodelling in 60% of the patients. A ROA > or = 0.20 cm(2) was associated with a lack of reverse remodelling, despite presenting similar baseline characteristics and a reduction in asynchrony to the other patients. Reverse remodelling was produced in all the other patients, with a significant reduction in end-systolic volume (41.7 +/- 21%; P = 0.003), accompanied by improvement in the ejection fraction (P = 0.003) and myocardial performance index (P = 0.027). CONCLUSION: CRT improved FMR, although the baseline presence of important mitral regurgitation, with a ROA > or = 0.20 cm(2), in patients undergoing CRT was associated with a lack of response in reverse remodelling.