Red blood cell distribution width (RDW) may serve as an integrative marker of pathological processes that portend worse prognosis in heart failure (HF). The prognostic value of RDW variation (ΔRDW) during hospitalization for acute heart failure (AHF) has yet to be studied.We retrospectively analyzed 2 independent cohorts: Centro Hospitalar do Porto (derivation cohort) and Lariboisière hospital (validation cohor...