ObjectiveTo determine the ability of cardiopulmonary exercise testing (CPET) to distinguish chronic thromboembolic pulmonary hypertension (CTEPH) from chronic thromboembolic disease (CTED). MethodsFifty patients diagnosed with CTED and fifty-eight patients with CTEPH in the the First Affiliated Hospital of Guangzhou Medical University from April 2019 to February 2022 were retrospectively included. The basic characteristics including age, gender, body mass index, symptom duration, and N-terminal prohormone of brain natriuretic peptide (NTpro-BNP), parameters of arterial blood gas analysis, right heart catheterization, echocardiography, pulmonary function, and CPET were all compared between patients with CTED and those with CTEPH. ResultsPatients with CTEPH displayed longer symptom duration, increased NTpro-BNP, decreased arterial partial pressure of oxygen, larger right atrial and ventricular diameters, and impaired worse resting pulmonary diffusing function compared with those with CTED (P<0.05). However, there was no statistically significant difference in the resting pulmonary ventilation function between the two groups (P>0.05). Among the CPET parameters of the CTEPH group, peak exercise oxygen uptake per kilogram, oxygen uptake at anaerobic threshold, oxygen pulse, oxygen uptake efficiency slope and oxygen saturation were all decreased, while the minute ventilation-carbon dioxide production at anaerobic threshold (VE/VCO2@AT) and VE/VCO2 slope were increased (P<0.05). However, there was no statistically significant difference in heart rate reserve and breathing reserve (P>0.05). Furthermore, VE/VCO2@AT showed high accuracy for distinguishing CTEPH from CTED (sensitivity, 0.825; specificity, 0.860; and the area under the receiver operating characteristic curve 0.897). ConclusionsPatients with CTEPH showed more significant decreased exercise endurance, diffusion dysfunction, and hypoxemia during exercise and insufficient increase in cardiac output compared with CTED patients. Therefore, it is feasible to apply CPET as a new objective examination to distinguish CTED from CTEPH.