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

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.

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.

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.