Association of Red Cell Distribution Width with Left Ventricular Ejection Fraction and Clinical Severity in Heart Failure: A Cross-sectional Study

Background: Heart failure (HF) remains a major global health burden with high morbidity and mortality. Identification of low-cost and widely available markers of disease severity is essential, particularly in resource-limited settings. Red cell distribution width (RDW), a routine haematological parameter, reflects erythrocyte size variability and has been linked to inflammation, oxidative stress and iron dysregulation in HF. This study evaluated the association of RDW with left ventricular ejection fraction (LVEF) and clinical severity in patients with HF. Methods: A cross-sectional study was conducted at a tertiary care hospital, including 90 adult patients with clinically and echocardiographically confirmed HF classified as the New York Heart Association (NYHA) class II-IV. RDW values were obtained from complete blood counts and LVEF was assessed using 2D echocardiography (Simpson’s biplane method). Patients with anaemia, hypothyroidism, chronic liver or renal disease, chronic obstructive pulmonary disease (COPD), alcoholism or autoimmune or inflammatory disorders were excluded. Statistical analysis included Pearson correlation, one-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve assessment. Results: The mean RDW-coefficient of variation (CV) was 17.04% ± 2.98% and the mean LVEF was 40.6% ± 12.1%. RDW demonstrated a strong negative correlation with LVEF ( r = –0.85, P < .001) and increased significantly with higher NYHA class (II: 13.17% ± 0.37%, III: 16.48% ± 2.19%, IV: 20.62% ± 1.69%; P < .001). Patients with reduced ejection fraction (<40%) had significantly higher RDW compared to those with preserved ejection fraction (EF) (18.92% ± 2.47% vs. 14.82% ± 1.71%; P < .001). RDW showed excellent discriminative ability for identifying reduced EF, with an area under the curve (AUC = 0.97). Conclusion: RDW, an inexpensive and universally available biomarker, strongly correlates with both echocardiographic (LVEF) and clinical (NYHA class) measures of HF severity. Although not a substitute for established biomarkers, RDW may serve as a practical adjunctive indicator for disease assessment, particularly in primary care and low-resource environments. Future prospective studies are warranted to define standardised cut-offs and validate its prognostic utility.