BackgroundElevated red blood cell distribution width (RDW) is a valid predictor of outcome in acute heart failure (AHF). It is unknown whether elevated RDW remains predictive in AHF patients with either preserved left ventricular ejection fraction (LVEF) ≥50% or reduced LVEF (<50%).Methods and resultsProspective local registry including 402 consecutive hospitalized AHF patients without acute coronary syndrome or need of intensive care. The primary outcome was all‐cause mortality (ACM) at 1 year after admission. Demographic and clinical data derive from admission, echocardiographic examinations (n = 269; 67%) from hospitalization.The Cox proportional hazard model including all patients (P < 0.001) was adjusted for age, gender, and RDW quartiles. Independent predictors of 1‐year ACM were cardiogenic shock (HR 2.86; CI: 1.3–6.4), male sex (HR 1.9; CI: 1.2–2.9), high RDW quartile (HR 1.66; CI: 1.02–2.8), chronic HF (HR 1.61; CI: 1.05–2.5), valvular heart disease (HR 1.61; CI: 1.09–2.4), increased diastolic blood pressure (HR 1.02 per mmHg; CI: 1.01–1.03), increasing age (HR 1.04 by year; CI: 1.02–1.07), platelet count (HR 1.002 per G/l; CI: 1.0–1.004), systolic blood pressure (HR 0.99 per mmHg; CI: 0.98–0.99), and weight (HR 0.98 per kg; CI: 0.97–0.99). A total of 114 patients (28.4%) died within the first year; ACM of all patients increased with quartiles of rising RDW (χ2 18; P < 0.001). ACM was not different between RDW quartiles of patients with reduced LVEF (n = 153; χ2 6.6; P = 0.084). In AHF with LVEF ≥50% the probability of ACM increased with rising RDW (n = 116; χ2 9.9; P = 0.0195).ConclusionsHigh RDW is associated with increased ACM in AHF patients with preserved but not with reduced LVEF in this study population.