Role of cardiopulmonary exercise test in the prediction of hemodynamic impairment in patients with pulmonary arterial hypertension.

Periodic repetition of right heart catheterization (RHC) in pulmonary arterial hypertension (PAH) can be challenging. We evaluated the correlation between RHC and cardiopulmonary exercise test (CPET) aiming at CPET use as a potential noninvasive tool for hemodynamic burden evaluation. One hundred and forty-four retrospective PAH patients who had performed CPET and RHC within 2 months were enrolled. The following analyses were performed: (a) CPET parameters in hemodynamic variables tertiles; (b) position of hemodynamic parameters in the peak end-tidal carbon dioxide pressure (P ET CO 2 ) versus ventilation/carbon dioxide output (VE/VCO 2 ) slope scatterplot, which is a specific hallmark of exercise respiratory abnormalities in PAH; (c) association between CPET and a hemodynamic burden score developed including mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), cardiac index, and right atrial pressure. VE/VCO 2 slope and peak P ET CO 2 significantly varied in mPAP and PVR tertiles, while peak oxygen uptake (peak VO 2 ) and O 2 pulse varied in the tertiles of all hemodynamic parameters. P ET CO 2 versus VE/VCO 2 slope showed a strong hyperbolic relationship ( R 2  = 0.7627). Patients with peak P ET CO 2  > median (26 mmHg) and VE/VCO 2 slope < median (44) presented lower mPAP and PVR (p < 0.005) than patients with peak P ET CO 2  < median and VE/VCO 2 slope > median. Multivariate analysis individuated peak VO 2 ( p  = 0.0158) and peak P ET CO 2 ( p  = 0.0089) as hemodynamic score independent predictors; the formula 11.584 - 0.0925 × peak VO 2  - 0.0811 × peak P ET CO 2 best predicts the hemodynamic score value from CPET data. A significant correlation was found between estimated and calculated scores ( p  < 0.0001), with a precise match for patients with mild-to-moderate hemodynamic burden (76% of cases). The results of the present study suggest that CPET could allow to estimate the hemodynamic burden in PAH patients.