Association of bioelectrical impedance phase angle with exercise tolerance in patients with chronic thromboembolic pulmonary hypertension

The relationship between exercise tolerance and body composition in chronic thromboembolic pulmonary hypertension (CTEPH) is not well-understood. This study assessed body composition and its link to the 6-min walk distance (6MWD) in 181 patients with CTEPH, analyzing 257 health status assessments from 2018 to 2021. Patients underwent right heart catheterization, bioelectrical impedance analysis for body composition, and 6MWD evaluations. The mean pulmonary arterial pressure and 6MWD were 20 mmHg (interquartile range [IQR]:16–25) and 414 m (IQR:354–490), respectively. The skeletal muscle index (SMI) and phase angle (PhA) were 6.4 kg/m2 (IQR: 5.7–7.2) and 4.4° (IQR: 4.0–5.1), respectively. The 6MWD was associated with age (β = –0.19; 95% confidence interval [CI]: –0.32, –0.07; p = 0.003), male sex (β = 0.22; 95% CI: 0.10, 0.34; p < 0.001), mean pulmonary arterial pressure (β = –0.32; 95% CI: –0.42, –0.21; p < 0.001), and PhA (β = 0.21; 95% CI: 0.06, 0.36; p = 0.005). However, SMI did not show any association with 6MWD. The study suggests PhA as a potential simple marker for exercise tolerance in patients with CTEPH, pending further validation for therapeutic targeting.