Mitral regurgitation and all-cause mortality in acute heart failure; a meta-analysis

AIMS: Despite previous studies investigating the impact of mitral regurgitation (MR) in acute heart failure (AHF) there are inconsistencies in trial data, and no meta-analyses to date. Our aim was to explore if MR is associated with mortality in AHF. METHODS AND RESULTS: We performed a meta-analysis of AHF patients with MR to investigate any association with all-cause mortality. We identified 27 studies that met our inclusion criteria, encompassing 73,363 patients (age 72.9±4.2years; females 44.4%) with an average follow-up of 1.9 years. Moderate/severe MR was associated with an unadjusted 47% increased mortality risk compared to no/mild MR (OR 1.47 [95% CI 1.30-1.66, p<0.001]). This excess risk of death persisted among studies reporting adjusted data (OR 1.21 [95% CI 1.01-1.45, p=0.038]). Compared to those with no MR, MR severity was associated with increasing risk of death: mild MR OR 1.22 [95% CI 0.98-1.53, p=0.079], moderate MR OR 1.48 [95% CI 1.1-2.01, p=0.011] and severe MR OR 1.60 [95% CI 1.13-2.27, p=0.008]. We observed excess mortality in moderate/severe MR compared to no/mild MR among individuals with a left ventricular ejection fraction (LVEF) <50% (OR 1.26 [95% CI 1.18-1.35, p<0.001]) and LVEF 40-50% (OR 2.00 [95% CI 1.59-2.50, p<0.001]) but not LVEF >50% (OR 1.16 [95% CI 0.91-1.47, p=0.23]. Neither meta-regression nor pre-specified sensitivity analyses affected MR's association with the primary outcome. A substantial degree of heterogeneity was observed across the included studies. CONCLUSIONS: We observed that MR during AHF is associated with increased mortality. Although causality cannot be inferred due to the observational design and high heterogeneity of the included studies, MR may represent a phenotype amenable to targeted therapies during decompensated heart failure.