Prognostic value of mitral regurgitation in patients with heart failure undergoing cardiac resynchronization therapy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac resynchronization therapy (CRT) is a well-established treatment for specific groups of heart failure (HF) patients. CRT improves outcomes in ischemic and non-ischemic HF patients, depending on different predictors. Mitral regurgitation (MR) is a common echocardiographic finding with uncertain reported impact on prognosis. Purpose We sought to investigate clinical outcomes in HF patient undergoing CRT according to MR severity, for both ischemic and non-ischemic HF etiology. A transthoracic echocardiogram was performed before and 1-year after device-based therapy to all patients (in doubtful cases, a cardiac magnetic resonance imaging was also performed to evaluate the mitral regurgitant volume). Methods Single-center retrospective study of consecutive patients submitted to CRT implantation. Patients were stratified attending to MR at baseline and after CRT, as having significant (moderate and severe MR) or non-significant MR. The primary endpoint was a composite of major adverse cardiac events (MACE), including HF hospitalization or all-cause mortality. Sustained ventricular arrhythmic events were the secondary endpoint. Results 117 HF patients (mean age 71.1 ± 10.6 years, males 67.5%) were enrolled, 31.6% had an ischemic HF etiology and 23.9% were included in the baseline significant MR (SMR) group. Regarding baseline characteristics, 40.2% had atrial fibrillation (AF), 23.9% obstructive pulmonary disease (COPD) and 9% peripheral artery disease (PAD). Patients in SMR group had more dyslipidemia (p = 0.026) and lower left ventricular ejection fraction (median 25% vs 32%, p = 0.001). At 1-year of follow-up, 11.1% had significant MR, most (61.5%) with the same MR baseline degree and presented with higher NYHA class (p = 0.032). During the follow-up, 15.4% reached the primary endpoint while 8.5% the secondary endpoint. Ischemic etiology (p = 0.204, p = 0.191) and the severity of baseline MR (p = 0.106, p = 0.213) did not predict any of the endpoints. On the contrary, male gender (p = 0.033), alcohol consumption (p = 0.003), PAD (p = 0.004) and COPD (p = 0.005) were independent predictors for MACE endpoint at a multivariable analysis. For the secondary endpoint, PAD (p = 0.020) and AF (p = 0.001) were both significant predictors. Significant MR after CRT implantation was an independent strong predictor only for MACE outcome (HR 4.37, p = 0.014). Conclusions Baseline significant MR was not associated with clinical outcomes after CRT implantation. However, MR at follow-up was a strong determinant of higher mortality and HF hospitalizations in more symptomatic patients, regardless of HF etiology.