To evaluate the sex differences of cardiopulmonary exercise testing (CPET) parameters in cardiac output (CO) prediction for patients with chronic thromboembolic pulmonary hypertension (CTEPH).

From May 2010 to February 2016, 73 cases (32 males and 41 females) with CTEPH were enrolled from Shanghai Pulmonary Hospital, all of whom underwent both right-heart catheterization and CPET.Multivariate regression analysis was applied to assess the prognostic value of CPET parameters.

Sex differences were of no significance in both demographic and hemodynamic parameters in total patients, but younger in female patients.Male patients had higher O₂ pulse at anaerobic threshold (AT), peak minute ventilation (VE), end-tidal partial pressure of oxygen output (PETO₂) at AT, peak O₂ pulse, VE at AT and nadir VE/carbon dioxide (VCO₂), but lower oxygen uptake efficiency slope compared with female patients (all P<0.05). There was no significant difference in CPET parameters between male event group and male event-free group, but peak oxygen uptake(VO₂)in female event group was lower than that in female event-free group (P<0.05). Female event group had lower peak VO₂, VE at AT and peak VE compared to the male event group (all P<0.05). Nadir VE/VCO₂ and peak PETO₂ were independent predictors of CO for male and female CTEPH patients, respectively.

The independent predictors of CPET parameters are different in the assessment of CO in male and female CTEPH patients, which suggests that sex differences of CPET should be considered to be the better clinical assessment of CTEPH patients.

Chronic thromboembolic pulmonary hypertension; Cardiopulmonary exercise testing; Sex characteristic; Cardiac output