Sex-specific cardiopulmonary exercise testing parameters as predictors in patients with idiopathic pulmonary arterial...

Cardiopulmonary exercise testing (CPET) has been used for prognosis in idiopathic pulmonary arterial hypertension (IPAH). We explored whether sex differences had an impact on prognostic assessments of CPET in IPAH. Data were retrieved from 21 male and 36 female incident IPAH patients who underwent both right heart catheterization and CPET from 2010 to 2016 at Shanghai Pulmonary Hospital. Cox proportional hazards analysis was used to assess the prognostic value of CPET. The mean duration of follow-up was 22±15 months. Nine men and 15 women had an event. The differences in clinical parameters in the whole population were not the same as the inter-subgroup differences. Event-free women had significantly higher cardiac output, lower pulmonary vascular resistance and percentage of predicted FVC compared with event men (all P<0.05). Event-free men had significantly higher end-tidal partial pressure of CO₂ (P_ETCO₂) at anaerobic threshold (AT), peak workload, P_ETCO₂, maximum oxygen consumption (VO₂)/minute ventilation (VE), and oxygen uptake efficiency slope and lower end-tidal partial pressure of O₂ (P_ETO₂) at AT, peak P_ETO₂, and lowest VE/VCO₂ compared with event men. Event-free women had dramatically higher peak VO₂, VCO₂, VE and O₂ pulse than event women (all P<0.05). Peak P_ETCO₂ was the independent predictor of event-free survival in all patients and males, whereas peak O₂ pulse was the independent predictor of event-free survival in females. Men with peak P_ETCO₂⩾20.50 mm Hg, women with peak O₂ pulse ⩾6.25 ml per beat and all patients with peak P_ETCO₂⩾27.03 mm Hg had significantly better event-free survival. Sex-specific CPET parameters are predictors of poor outcomes. Decreased peak P_ETCO₂ in men and peak O₂ pulse in women were associated with lower event-free survival in IPAH.