Prognostic Impact of Iron Deficiency in New-Onset Chronic Heart Failure: Danish Heart Failure Registry Insights

AIMS: Iron deficiency (ID) is prevalent in chronic heart failure (HF) but lacks a consensus definition. This study evaluates the prevalence and the prognostic impact of ID using different criteria on all-cause and cardiovascular mortality, as well as first hospitalization for HF in patients with new-onset chronic HF. METHODS: In this nationwide registry-based cohort, we explored four definitions of ID: the current European Society of Cardiology (ESC) guidelines ferritin 13 μmol/L and TSAT > 20%. Regardless of anaemia status, ID defined by TSAT < 20% or serum iron ≤13 μmol/L was associated with all-cause mortality [non-anaemic, hazard ratio (HR): 1.57, 95% confidence interval (CI): 1.30-1.89 and HR: 1.47, 95% CI: 1.24-1.73; anaemic, HR: 1.22, 95% CI: 1.07-1.38 and HR: 1.25, 95% CI: 1.09-1.44, respectively and cardiovascular mortality (non-anaemic, HR: 2.21, 95% CI: 1.59-3.06 and HR: 1.47, 95% CI: 1.12-1.95; anaemic, HR: 1.37, 95% CI: 1.11-1.69 and HR: 1.28, 95% CI: 1.02-1.61, respectively), as well as increased risk of first hospitalization for HF (non-anaemic, HR: 1.28, 95% CI: 1.09-1.1.50 and HR: 1.27, 95% CI: 1.10-1.46; anaemic, HR: 1.25, 95% CI: 1.08-1.44 and HR: 1.22, 95% CI: 1.05-1.42, respectively). ID defined by ESC guidelines was associated with all-cause and cardiovascular mortality only in non-anaemic patients (HR: 1.41, 95% CI: 1.18-1.1.70 and HR: 1.58, 95% CI: 1.18-2.12.). Furthermore, the ESC guideline definition was associated with increased risk of first hospitalization for HF, regardless of anaemia status (non-anaemic, HR: 1.26, 95% CI: 1.08-1.1.47; anaemic, HR: 1.34, 95% CI: 1.17-1.53). CONCLUSIONS: ID, when defined by TSAT < 20% or serum iron ≤13 μmol/L, is associated with increased risk of all-cause and cardiovascular mortality, as well as first hospitalization for HF in patients with new-onset chronic HF, regardless of anaemia status. Conversely, ID defined as ESC guidelines is associated with all-cause and cardiovascular mortality only in non-anaemic patients.