Repletion of iron stores with the use of oral iron supplementation in patients with systolic heart failure
Reviewer: Dr. Alan Gaby, MD
Author: Niehaus ED, et al
Reference: Repletion of iron stores with the use of oral iron supplementation in patients with systolic heart failure. J Card Fail 2015;21:694-697.
Design: Retrospective study.
Participants: One hundred five patients (mean age, 69 years) with iron deficiency (defined below) and heart failure who had been treated with oral iron.
Study Medication and Dosage: Oral iron at a mean daily dose of 130 mg (range, 65-150 mg).
Primary Outcome Measures: Laboratory indicators of iron status.
Key Findings: After a median treatment period of 164 days, the median value for ferritin increased from 39 µg/L to 75 µg/L and transferrin saturation increased from 10% to 21%. When compared with changes in heart failure patients resulting from intravenous iron in an earlier clinical trial, the increases in transferrin saturation were similar with oral and intravenous iron, but the increases in ferritin levels were markedly greater with intravenous iron.
Practice Implications: In addition to being a component of hemoglobin, iron is a cofactor for the enzyme cytochrome oxidase, which plays a role in mitochondrial ATP production. ATP is essential for the pumping action of the heart; therefore, iron deficiency could exacerbate heart failure whether or not the patient is anemic. Patients with heart failure are considered to have absolute iron deficiency if their serum ferritin level is below 100 µg/L. This cut-off level is well above that used to diagnose iron deficiency in healthy individuals. The higher value takes into account the fact that heart failure is associated with chronic inflammation, and that serum ferritin levels rise in response to inflammation. Heart failure patients are thought to have functional (as opposed to absolute) iron deficiency if their serum ferritin level is between 100 and 300 µg/L (which is frequently seen in patients with chronic inflammatory diseases) and their transferrin saturation is below 20%.
As many as 50% of heart failure patients have absolute or functional iron deficiency according the above definitions. Iron deficiency (irrespective of anemia) is a strong predictor of mortality in these patients. In clinical trials, intravenous administration of iron to heart failure patients with iron deficiency improved functional capacity, decreased the number of hospitalizations, and possibly decreased mortality.  Intravenous iron therapy is expensive and is also not widely available. Although oral iron is often poorly absorbed by patients with heart failure, the results of the present study suggest that oral iron supplements would provide some benefit.
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