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Functional iron deficiency in symptomatic HFrEF without anemia — ABIM Board MCQ

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HardHeart Failure with Reduced Ejection FractionFunctional iron deficiency in symptomatic HFrEF without anemiaABIM Board

A 68-year-old woman with nonischemic heart failure with reduced ejection fraction is evaluated for persistent fatigue and exertional dyspnea. She becomes short of breath while walking one block but has no symptoms at rest. Her medications are maximally tolerated sacubitril-valsartan, carvedilol, spironolactone, dapagliflozin, and furosemide. She has taken all medications consistently. Blood pressure is 106/68 mm Hg, pulse is 66/min and regular, and oxygen saturation is 97% on room air. Jugular venous pressure is normal, and the lungs are clear; there is no peripheral edema. Echocardiography shows a left ventricular ejection fraction of 30%, unchanged from 6 months ago. Laboratory studies show hemoglobin 12.8 g/dL, mean corpuscular volume 88 fL, ferritin 186 ng/mL, transferrin saturation 14%, creatinine 1.3 mg/dL, and estimated glomerular filtration rate 44 mL/min/1.73 m². She has had no overt bleeding, and age-appropriate gastrointestinal evaluation is current. Which of the following is the most appropriate adjunctive treatment to improve her exercise capacity?

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Correct answer: E — Administer intravenous ferric carboxymaltose

This patient has symptomatic, euvolemic NYHA class III HFrEF despite comprehensive guideline-directed medical therapy. Her ferritin may appear adequate, but ferritin is an acute-phase reactant and can overestimate available iron in heart failure. A ferritin of 100–299 ng/mL with transferrin saturation below 20% meets the established heart-failure definition of functional iron deficiency. Anemia is not required. Intravenous ferric carboxymaltose is therefore appropriate to improve exercise capacity, functional status, and quality of life. It should not be presented as established mortality therapy; recent trials have not consistently reduced cardiovascular death or heart-failure hospitalization. Oral ferrous sulfate is attractive because the hemoglobin is normal and deficiency appears modest, but high-dose oral iron did not improve exercise capacity in the IRONOUT-HF trial. Darbepoetin is not indicated because she is not anemic, and erythropoiesis-stimulating agents do not improve heart-failure outcomes and may increase thromboembolic risk. Red-cell transfusion is inappropriate with a hemoglobin of 12.8 g/dL and no bleeding or tissue hypoxia. Waiting for anemia misses the distinction between iron deficiency and anemia: iron deficiency itself is a treatable contributor to impaired functional capacity in symptomatic HFrEF.

Reference: 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure (2022) — https://www.heart.org/-/media/832EA0F4E73948848612F228F7FA2D35.pdf Injectafer (ferric carboxymaltose) prescribing information (2025) — https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/203565s027lbl.pdf Effect of Oral Iron Repletion on Exercise Capacity in Patients With Heart Failure With Reduced Ejection Fraction and Iron Deficiency: The IRONOUT HF Randomized Clinical Trial (2017) — https://pubmed.ncbi.nlm.nih.gov/28510680/