Iron deficiency predicts impaired exercise capacity in patients with systolic chronic heart failure.

Abstract Background Iron is an indispensable element of hemoglobin, myoglobin, and cytochromes, and, beyond erythropoiesis, is involved in oxidative metabolism and cellular energetics. Hence, iron deficiency (ID) is anticipated to limit exercise capacity. We investigated whether ID predicted exercise intolerance in patients with systolic chronic heart failure (CHF). Methods and Results We prospectively studied 443 patients with stable systolic CHF (age 54 ± 10 years, males 90%, ejection fraction 26 ± 7%, New York Heart Association Class I/II/III/IV 49/188/180/26). ID was defined as: serum ferritin 2 ) and ventilatory response to exercise (VE-VCO 2 slope). ID was present in 35 ± 4% (±95% confidence interval) of patients with systolic CHF. Those with ID had reduced peak VO 2 and increased VE-VCO 2 slope as compared to subjects without ID (peak VO 2 : 13.3 ± 4.0 versus 15.3 ± 4.5 mL•min•kg, VE-VCO 2 slope: 50.9 ± 15.8 versus 43.1 ± 11.1, respectively, both P P 2 (β = −0.14, P P 2 slope (β = 0.14, P P 2 and VE-VCO 2 slope ( P Conclusions ID independently predicts exercise intolerance in patients with systolic CHF, but the strength of these associations is relatively weak. Whether iron supplementation would improve exercise capacity in iron-deficient subjects requires further studies.