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 tack 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 >= 10% in end-systolic volume) according to the presence or absence of important FMR, defined as a regurgitant orifice area (ROA) of >= 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 >= 0.20 cm(2) was associated with a tack 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 >= 0.20 cm(2), in patients undergoing CRT was associated with a lack of response in reverse remodelling.