Functional Iron Deficiency in Patients With Heart Failure: A Focus on Its Prevalence Among Hospitalized Patients and...

Background Iron deficiency (ID) is common in heart failure (HF) and is present in up to 80% of hospitalized patients. The majority of the studies have focused on describing patients with low ferritin levels. We studied functional iron deficiency (FID) in heart failure in a single-center observational study, with a focus on its relevance in the current era and its impact on outcomes in hospitalised patients. Methods Patients with HF and normal hemoglobin were considered and divided into 2 groups: absolute ID (serum ferritin < 100 mg/L) and FID (normal serum ferritin, i.e., 100-300 mg/L with low transferrin saturation (TSAT; <20%). Anemia was defined as hemoglobin (Hb) <13 g/dl for males and <12 g/dl for females. Patients were classified into four HF classes based on ejection fraction (EF). EF of ≥50% was taken as HFpEF (heart failure with preserved ejection fraction), 41-49% EF as HFmrEF (heart failure with mildly reduced ejection fraction), and EF <40% as HFrEF (heart failure with reduced ejection fraction). A one-year follow-up was done to assess the New York Heart Association (NYHA) functional class, hemoglobin levels, and recurrent hospitalizations (if any). Results In total, 53 patients, of whom 43 (81%) were males and 10 (19%) were females, were studied. Follow-up data of 29 patients showed outcomes such as deaths (n=6; 11%), recurrent hospitalization for HF (8 patients; 24%), and prolonged hospital stay (n=1). Twenty-four patients (45%) showed clinical improvement on follow-up, among whom 15 patients (62.5%) received IV iron supplementation. Conclusion Functional ID, as determined by low TSAT, represents a significant proportion of HF who are iron-deficient. These patients have outcomes similar to those of patients with normal iron levels. IV iron supplementation resulted in symptomatic improvement; however, this was not statistically significant. In view of this, we hypothesize that the term "functional iron deficiency" may not be deemed relevant in the context of HF, especially in the presence of multiple other factors influencing iron levels. Further large-scale studies are needed to establish this.