The water imbalance of skeletal muscle and muscle weakness in patients with heart failure.

Aims: A high extracellular water (ECW) to intracellular water (ICW) ratio of skeletal muscle as assessed by bioelectrical impedance analysis is reportedly associated with loss of muscle strength. However, the validity of this index for heart failure (HF), which is likely associated with changes in the water distribution, is unclear.

Methods And Results: This study involved 190 patients with HF. The total ECW and ICW of both upper and lower extremities were measured, and a high ECW/ICW ratio was defined as an ECW/ICW ratio higher than the median (≥0.636 for men, ≥0.652 for women). Low muscle strength was defined as reduced handgrip strength according to the criteria established by the Asian Working Group for Sarcopenia. Patients with a high ECW/ICW ratio had a lower handgrip strength (21.1 ± 8.1 kg vs. 27.6 ± 9.3 kg, P ≤ 0.05) and 6 min walk distance (329 ± 116 m vs. 440 ± 114 m) than those with a low ECW/ICW ratio. An increasing ECW and/or decreasing ICW was associated with a higher ECW/ICW ratio and a lower handgrip strength (P < 0.05). In the multivariate logistic regression analysis, a high ECW/ICW ratio and low skeletal muscle mass were independently associated with low muscle strength (P < 0.05).

Conclusions: A high ECW/ICW ratio in limb muscles, that is, the water imbalance of increasing ECW and/or decreasing ICW, is useful in assessing muscle quality in patients with HF.