Objective: To determine the accuracy of cardiopulmonary exercise-testing (CPET) in detecting exercise-induced pulmonary hypertension.
Background: CPET plays a key role in the investigation of exertional breathlessness. Exercise-induced pulmonary hypertension has been recently demonstrated to be a cause of exertional dyspnea. However, the features of CPET associated with the condition are still unknown.
Methods: We prospectively studied CPET and exercise echo-cardiography characteristics in 39 patients complaining of exertional breathlessness. Patients could be divided into 3 groups as follows: 1) control subjects having normal pulmonary arterial pressure at rest [pulmonary arterial systolic pressure < 35 mmHg] and at peak exercise [pulmonary arterial systolic pressure < 45 mmHg]; 2) patients having exercise-induced PH; 3) patients having resting PH. Results from CPET have been analyzed within each group.
Results: Patients developing exercise-induced PH revealed an increased VD/VT ratio and CO2 gradient (P[a-ET]CO2) at peak exercise compared to controls (VD/VT at 0.38 +/- 0.1 vs 0.29 +/- 0.11 and P[a-ET]CO2 at 4,6 +/- 3,1 vs 1 +/- 3,8 mmHg). VD/VT and P[a-ET]CO2 were increased in patients with resting PH. A VD/VT ratio at peak exercise higher than 0.34 was 72.7% sensitive and 71% specific in predicting exercise-induced PH. Positive and negative predictive values were 72.7% and 70.1% respectively.
Conclusion: Patients with exercise-induced PH did not decrease or may increase dead space during exercise. Therefore CPET may be a useful tool in selecting patients who need to undergo further exercise haemodynamic investigations.