Cardio-pulmonary exercise testing (CPET) is a hallmark diagnostic tool to assess functional capacity and prognosis in pulmonary hypertension. It has been shown that pulmonary hemodynamics and functional class are associated with key CPET parameters. However, the association with invasively measured load-independent contractility (End-systolic elastance (Ees)), afterload (arterial elastance (Ea)), RV-arterial coupling (Ees/Ea) and RV diastolic stiffness (end-diastolic elastance (Eed)) and cardiac magnetic resonance imaging parameters reflecting stiffness of the pulmonary arteries in patients with pulmonary hypertension (PH) has not been investigated so far.
We performed cardio-pulmonary exercise testing, cardiac magnetic resonance imaging and invasive measurement of pulmonary haemodynamics and conductance catheter-derived single-beat RV pressure and volume loops in 38 patients with PH.
Ea, Eed and parameters reflecting stiffness of the pulmonary arteries (capacitance/distensibility) were significantly associated with Ve/VCO2-Slope and peak end-tidal carbon dioxide. Using receiver operating characteristic analyses and the Youden index, we identified an Ea cut-off of 0.75 mmHg·mL–1 mm·mmHg−1 (sensitivity: 84.6%; specificity: 65.2%) and Eed cut-off of 0.17 mmHg·mL–1 (sensitivity: 76.9%; specificity: 82.6%) for discriminating ventilatory inefficiency (Ve/VCO2-Slope >48).
Right ventricular diastolic dysfunction, increased afterload and stiffness of the pulmonary arteries showed an association with ventilatory inefficiency and may thus contribute to dyspnoea in PH. A putative link with compromised survival in these patients needs to be further investigated.