High Extracellular-to-Intracellular Water Ratio in Limb Muscles is Associated with Low Muscle Strength in Patients with Heart Failure

BackgroundA 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. MethodsThis 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 ([&ge;]0.636 for men, [&ge;]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. ResultsPatients with a high ECW/ICW ratio were older, had a higher left ventricular ejection fraction and B-type natriuretic peptide level, and had a lower body mass index, hemoglobin level, albumin level, estimated glomerular filtration rate, handgrip strength, and 6-minute walk distance than patients with a low ECW/ICW ratio (p < 0.05). An increasing ECW and/or decreasing ICW was associated with a higher ECW/ICW ratio (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). ConclusionA high ECW/ICW ratio in limb muscles (i.e., an increasing ECW and/or decreasing ICW) is independently associated with muscle weakness regardless of skeletal muscle mass in patients with HF. What Is New?{diamondsuit} A high extracellular water (ECW) to intracellular water (ICW) ratio of skeletal muscle as assessed by bioelectrical impedance analysis was independently associated with low muscle strength regardless of skeletal muscle mass in patients with heart failure (HF). {diamondsuit}Both an increasing ECW and decreasing ICW were independently associated with low muscle strength in patients with HF. What Are the Clinical Implications?{diamondsuit} The ECW/ICW ratio in limb muscles is a new index that can be used to assess muscle function apart from muscle mass in patients with HF.