Iron status, catabolic/anabolic balance, and skeletal muscle performance in men with heart failure with reduced ejection fraction.

BACKGROUND: Metabolic derangements related to tissue energetics constitute an important pathophysiological feature of heart failure. We investigated whether iron deficiency and catabolic/anabolic imbalance contribute to decreased skeletal muscle performance in men with heart failure with reduced ejection fraction (HFrEF), and whether these pathologies are related to each other.

METHODS: We comprehensively examined 23 men with stable HFrEF (median age [interquartile range]: 63 [59-66] years; left ventricular ejection fraction: 28 [25-35]%; New York Heart association class I/II/III: 17/43/39%). We analyzed clinical characteristics, iron status, hormones, strength and fatigability of forearm flexors and quadriceps (surface electromyography), and exercise capacity (6-minute walking test).

RESULTS: None of the patients had anemia whereas 8 were iron-deficient. Flexor carpi radialis fatigability correlated with lower reticulocyte hemoglobin content (CHR, p < 0.05), and there was a trend towards greater fatigability in patients with higher body mass index and lower serum ferritin (both p < 0.1). Flexor carpi ulnaris fatigability correlated with lower serum iron and CHR (both p < 0.05). Vastus medialis fatigability was related to lower free and bioavailable testosterone (FT and BT, respectively, both p < 0.05), and 6MWT distance was shorter in patients with higher cortisol/FT and cortisol/BT ratio (both p < 0.05). Lower ferritin and transferrin saturation correlated with lower percentage of FT and BT. Men with HFrEF and ID had higher total testosterone, but lower percentage of FT and BT.

CONCLUSIONS: Iron deficiency correlates with lower bioactive testosterone in men with HFrEF. These two pathologies can both contribute to decreased skeletal muscle performance in such patients.