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Significant mitral regurgitation as a predictor of long-term prognosis in patients receiving cardiac resynchronisation therapy.

BACKGROUND
Cardiac resynchronisation therapy (CRT) has been shown to reduce functional mitral regurgitation, although the relationship between significant mitral regurgitation (SMR) and the clinical prognosis of CRT remains uncertain.


AIM
We sought to investigate the association of baseline SMR with long-term outcomes in patients undergoing CRT.


METHODS
A total of 296 consecutive patients undergoing CRT were enrolled. SMR was quantified by colour Doppler in all patients at baseline and defined as level ≥ 3 on the severity scale. The primary endpoints included all-cause death, heart failure hospitalisation (HFH), and heart transplantation, and the secondary endpoints were response to CRT and New York Heart Association (NYHA) class III or IV six months after CRT implantation.


RESULTS
The mean age was 59 ± 11 years, and 202 (68.2%) patients were male. Among all patients, 124 (41.9%) presented with baseline SMR. Over a mean follow-up of 4.17 ± 3.16 years, there were 53 (17.9%) cases of all-cause death, 41 (13.8%) cases of HFH, and four (1.4%) cases of heart transplantation. SMR was positively associated with primary endpoint events (hazard ratio [HR] 1.602, 95% confidence interval [CI] 1.083-2.371, p = 0.019), HFH (HR 3.567, 95% CI 1.763-7.219, p < 0.001) and NYHA class III or IV (HR 2.101, 95% CI 1.313-3.363, p = 0.002). After adjusting for multiple factors, we found that SMR (HR 1.785, 95% CI 1.091-2.920, p = 0.021), ischaemic heart disease (HR 1.628, 95% CI 1.062-2.494, p = 0.025), and the lack of use of spironolactone (HR 2.044, 95% CI 1.040-4.017, p = 0.038) were independent predictors of primary endpoints, and SMR remained an independent predictor of HFH (HR 4.622, 95% CI 1.955-10.923, p < 0.001).


CONCLUSIONS
Significant mitral regurgitation before CRT implantation was strongly associated with long-term poor progno-sis. SMR was positively associated with HFH rather than all-cause death and CRT response.