Objective: To evaluate the application value of cardiopulmonary exercise testing in patients with chronic thromboembolic pulmonary hypertension (CTEPH).
Methods: A total of 116 consecutive patients admitted into the Cardiology Department of Fuwai Hospital.They were divided into 3 groups of CTEPH (n = 44), CPE (without pulmonary hypertension in chronic pulmonary embolism) (n = 24) and control (without pulmonary embolism or pulmonary hypertension) (n = 48) respectively. Their levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured. Incremental cardiopulmonary exercise testing was performed to compare its differential results among 3 groups and evaluate the correlation between NT-proBNP and its parameters.
Results: The body mass index (BMI) in the CTEPH group was lower than those in the CPE and control groups ((23.8 ± 3.9) vs (26.1 ± 3.6) and (26.7 ± 3.2) kg/m(2) ), both P < 0.05); the medical history in the CTEPH group was longer than those in the CPE and control groups ((58 ± 48) vs (12 ± 10) and (29 ± 25) months, both P < 0.05). The plasma concentrations of NT-proBNP in the CTEPH group were higher than those in the CPE and control groups ((1678 ± 1255) vs (577 ± 167) and (608 ± 247) pmol/L, both P < 0.05). All of them completed the test and there were no severe complications such as syncope or exacerbation of disease. Maximum oxygen consumption (VO2max), percentage of predicted maximum oxygen consumption (VO2 %), oxygen consumption in relation to body weight (VO2/kg), anaerobic threshold and O2 pulse in the CTEPH group were significantly lower than those in the CPE and control groups (P < 0.05). The ratios of dead space volume (VD) to tidal volume (VT) in the CTEPH and CPE groups were higher than those in the control group (P < 0.05). The plasma concentrations of NT-proBNP were inversely correlated with right ventricular internal diameter (r = -0.690, P = 0.000) and VO2/kg (r = -0.496, P = 0.000). The right ventricular internal diameter (β = 0.583, P = 0.000) and VO2/kg (β = 0.233, P = 0.032) were strong independent determinants of NT-proBNP.
Conclusion: As a reliable pathophysiological indictor of CTEPH, cardiopulmonary exercise testing may be used objectively and safely to evaluate the cardiopulmonary function of CTEPH patients.