Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 21 3 2026 05 31 203 213 Mohammad Javad Alborzi General cardiologist, Rajaie Cardiovascular Institute, Tehran, Iran Nasim Naderi Professor of Cardiology, Fellowship in Heart Failure and Transplantation, Rajaie Cardiovascular Institute, Tehran, Iran Mohammad Reza Baay Assistant Professor of Cardiology, Interventional Cardiology, Rajaie Cardiovascular Institute, Tehran, Iran Sepideh Taghavi Professor of Cardiology, Fellowship in Heart Failure and Transplantation, Rajaie Razieh Omidvar Assistant Professor of Cardiology, Fellowship in Heart Failure and Transplantation, Rajaie Marzieh Mirtajaddini Assistant Professor of Cardiology, Fellowship in Heart Failure and Transplantation, Rajaie Cardiovascular Institute, Tehran, Iran Hooman Bakhshandeh Professor of Epidemiology, Cardiovascular Epidemiology Research Center, Rajaie Cardiovascular Medical and Research Institute, Tehran, Iran 2025 12 29 2026 05 31 Background: Hospitalizations for acute decompensated heart failure (ADHF) impose a substantial health care burden, and prognosis worsens with each readmission. Identifying patients at risk of frequent hospitalization is therefore essential. Red blood cell distribution width (RDW) has recently gained attention as a prognostic biomarker in cardiovascular disease. This study evaluated the prognostic value of baseline RDW and its in-hospital changes in patients admitted with ADHF. Methods: In this retrospective observational cohort study, all adults hospitalized with ADHF between March 2022 and August 2024 were assessed. Demographic, clinical, echocardiographic, and laboratory data–including admission RDW and in-hospital RDW measurements–were extracted from the hospital information system and medical records. Early readmission for HF within 30 days after discharge was defined as the primary end point, and in-hospital mortality as the secondary end point. Results: Among 1871 hospitalization records from 1409 patients (66.9% male; mean [SD] age, 59.3 [12.4] years), 984 cases with available follow-up data were analyzed. The mean length of stay (LOS) was 9.5 days, and the mean New York Heart Association (NYHA) class was 3.3. Early readmission occurred in 201 records (20.4% of admissions, 22% of patients). Baseline RDW independently predicted both outcomes: each 1-unit increase in RDW was associated with an 11% higher risk of early readmission and a 16% higher risk of in-hospital mortality. Additionally, a 1-unit increase in the change in RDW from admission to last measurement (ΔRDW) and the ratio of ΔRDW to LOS (ΔRDW/LOS) was linked to a 1.3-fold and 2.3-fold higher mortality risk, respectively. Conclusion: Baseline RDW on admission is a strong, independent predictor of both early readmission and in-hospital mortality in patients with ADHF. RDW may serve as a simple and cost-effective marker for risk stratification and early intervention in this population. https://rhythm.tums.ac.ir/index.php/jthc/article/view/2421 https://rhythm.tums.ac.ir/index.php/jthc/article/download/2421/1273