Reduced Cardiorespiratory Fitness and Its Physiological Determinants in Patients With Cirrhosis: Evidence of Cirrhosis-Induced Myopathy.

Abstract

Background: Cirrhosis induces multi-organ dysfunction, yet the specific physiological determinants underlying reduced cardiorespiratory fitness (CRF) remain poorly defined.

Aim: To compare patients with cirrhosis to healthy controls to assess and identify their major CRF physiological contributors.

Methods: Forty-five patients with cirrhosis and 45 age- and sex-matched controls underwent incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer. The pulmonary, cardiac, vascular, and muscular components of CRF were measured, including peak oxygen uptake (VO_2Peak), ventilatory efficiency (VE/VCO₂), oxygen uptake efficiency slope (OUES), and chronotropic response. Non-invasive hemodynamic monitoring (Physioflow) was used to estimate cardiac output and arteriovenous oxygen difference (a-vO₂).

Results: Patients with cirrhosis exhibited markedly reduced CRF compared with controls (VO_2Peak: 15.4 ± 5.5 vs. 29.3 ± 7.5 mL.min^-1.kg^-1, p < 0.001) and the decline was proportional to Child-Pugh score. Kinetic parameters (OUES, Lowest VE/VCO₂, Wilkoff index) were also significantly impaired and chronotropic incompetence was highly prevalent (89%). Cardiac output was preserved but a-vO₂ was lower (10.7 ± 3.0 vs. 14.1 ± 1.1 mlO₂.dL^-1, p = 0.002), indicating a defective peripheral oxygen extraction in patients with cirrhosis. Multivariate regression analysis (r² = 0.79) identified maximal heart rate and muscle performance (5-sit to stand) as independent predictors of VO_2Peak.

Conclusion: Reduced CRF in cirrhosis appears to primarily result from impaired skeletal muscle oxygen utilization, compounded by chronotropic incompetence. These findings emphasize the value of integrative functional evaluation in cirrhosis management.