Value of cardiopulmonary exercise testing in comparing cardio-pulmonary function among patients with three kinds of pulmonary artery hypertension

Abstract

To assess the exercise capacity of three kinds of pulmonary artery hypertension using cardiopulmonary exercise testing (CPET). In the Center for Pulmonary Vascular Disease Diagnosis and Treatment of Fuwai Hospital, idiopathic pulmonary artery hypertension (IPAH), congenital heart disease associated pulmonary artery hypertension (CHD-PAH), connective tissue disease associated pulmonary artery hypertension (CTD-PAH) were enrolled into this study from December 2012 to May 2013. CPET was performed in all patients, and clinical features, routine tests results, N-terminal B-type natriuretic peptide (NT-proBNP), Six-minutes-walk distance (6MWD) were all collected. Thirty-two patients with IPAH, 38 patients with CHD-PAH, 25 patients with CTD-PAH were enrolled. For IPAH, CHD-PAH, and CTD-PAH patients, the peak oxygen uptake via body weight (VO₂max/kg) was (12.3 ± 2.3), (14.9 ± 4.0), and (11.1 ± 2.5) ml·min⁻¹·kg⁻¹, respectively. The peak VO₂/kg was significantly different within these three groups (P<0.001), and was significantly higher in CHD-PAH patients compared with the other two groups (P=0.003, P<0.001). The peak VO2/heart rate (HR) was (5.8±1.4), (6.4 ± 1.8), (5.3 ± 1.7) ml·beat(-1)·min⁻¹ in the above three groups and was significantly different within these three groups (P=0.034). The peak VO₂/HR was significantly increased in CHD-PAH patients than CTD-PAD patients (P=0.012). The peak HR was (136.1 ± 21.4), (140.8 ± 19.9), (124.5 ± 21.6) beat/min respectively and was significantly lower in CTD-PAD patients than CHD-PAH patients (P=0.009). The 6MWD was significantly decreased in CTD-PAD patients compared with CHD-PAH and IPAH patients (P=0.006, 0.010). Nt-proBNP was significantly decreased in CTD-PAD patients compared with CHD-PAH patients (P=0.012). In Pearson and partial correlation analysis, the peak VO₂/kg was significantly correlated with peak VO₂/HR, peak HR, 6MWD, Nt-proBNP, left ventricular end-diastolic diameter, right ventricular end-diastolic diameter (r=0.477, 0.518, 0.387, 0.465, -0.350, 0.349, -0.259). CPET parameters can objectively evaluate exercise capacity and cardiopulmonary function of the patients with pulmonary hypertension.