Impact of various iron deficiency definitions on mortality risk in chronic heart failure across the spectrum of left ventricular ejection fraction spectrum

Abstract Introduction Iron deficiency (ID) is prevalent in chronic heart failure (HF) but lacks a consensus definition. Purpose This study evaluates the prevalence of ID and its association with all-cause mortality and first hospitalization for HF, using current European Society of Cardiology (ESC) guidelines, transferrin saturation (TSAT) <20%, ferritin <100 ng/ml, and serum iron ≤13 μmol/L as ID criteria. Methods and Results Of 8587 new-onset HF patients registered in the Danish Heart Failure Registry from April 2003 to July 2021, we found varying ID prevalence (35.4% to 67%) based on different definitions. In heart failure with reduced ejection fraction (HFrEF) patients, irrespective of anemia, ID defined by TSAT <20% and serum iron ≤13 μmol/L was associated with all-cause mortality (non-anemic, HR: 1.42, 95% CI:1.22-1.64 and HR: 1.25, 95% CI: 1.1-1.43; anemic, HR: 1.22, 95% CI: 1.1-1.35 and HR: 1.26, 95% CI: 1.12-1.41, respectively) and first HF hospitalization (non-anemic, HR:1.41, 95% CI:1.23-1.62, HR: 1.33, 95% CI: 1.18-1.51; anemic, HR:1.27, 95% CI:1.12-1.45 and HR: 1.26, 95% CI:1.09-1.45, respectively). ID per ESC guidelines was only associated to mortality in non-anemic HFrEF (HR: 1.24, 95% CI:1.09-1.42) and first HF hospitalization in HFrEF, irrespective of anemia (non- anemic, HR:1.24, 95% CI:1.09-1.42; anemic, HR:1.35, 95% CI:1.2-1.52). No association was observed between the various definitions and outcomes in patients with heart failure with mildly reduced ejection fraction and heart failure with preserved ejection fraction. Conclusion ID, when defined by TSAT <20% or serum iron ≤13 μmol/L, is associated with increased mortality and first hospitalization in HFrEF patients, regardless of anemia. Conversely, ID as per ESC guidelines is associated with mortality in non-anemic HFrEF patients and first hospitalization in HFrEF, irrespective of anemia status.Figure 1:Forest plot mortalityFigure 2:Forest plot hospitalization