Objectives: This study investigates the prevalence and prognostic significance of mitral regurgitation (MR) in acute decompensated heart failure (ADHF) patients. Background: Few studies characterize the burden of MR in heart failure. Methods: The ARIC (Atherosclerosis Risk In Communities) study surveilled ADHF hospitalizations for residents ≥55 years of age in 4 U.S. communities. ADHF cases were stratified by left ventricular ejection fraction (LVEF): <50% and ≥50%. Odds of moderate or severe MR in patients with varying sex and race, and odds of 1-year mortality in those with higher MR severity were estimated using multivariable logistic regression. Results: From 2005 to 2014, there were 17,931 weighted ADHF hospitalizations of which 49.2% had an LVEF <50% and 50.8% an LVEF ≥50%. Moderate or severe MR prevalence was 44.5% in those with an LVEF <50% and 27.5% in those with an LVEF ≥50%. Moderate or severe MR was more likely in females than males regardless of LVEF; LVEF <50% (odds ratio [OR]: 1.21 [95% confidence interval (CI): 1.11 to 1.33]), LVEF ≥50% (OR: 1.52 [95% CI: 1.36 to 1.69]). Among hospitalizations with an LVEF ≥50%, moderate or severe MR was less likely in blacks than whites (OR: 0.72 [95% CI: 0.64 to 0.82]). Higher MR severity was independently associated with increased 1-year mortality in those with an LVEF <50% (OR: 1.30 [95% CI: 1.16 to 1.45]). Conclusions: Patients with ADHF have a significant MR burden that varies with sex and race. In ADHF patients with an LVEF <50%, higher MR severity is associated with excess 1-year mortality
