Exercise right atrial pressure is associated with markers of disease severity in different types of pulmonary hypertension

Background: Right atrial pressure (RAP) at rest is an established measure of right ventricular function and a prognostic marker in precapillary pulmonary hypertension (PH). However, the potential prognostic role of RAP measured during exercise (exRAP) is not well described in patients diagnosed with PH according to the recently introduced definition of mean pulmonary artery pressure (mPAP) >20 mmHg. The primary objective of the present study was to investigate associations between exRAP and markers of disease severity and prognosis in different PH types.

Methods: Consecutive patients undergoing exercise right heart catheterization for evaluation of PH at one single centre were analysed. Associations between RAP parameters (absolute exRAP values and the difference between resting RAP and exRAP (deltaRAP)) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, other haemodynamic parameters during exercise, and the "ESC/ERS 3 risk-strata model" for patients with PH were investigated. 

Results: A total of 128 patients with complete haemodynamic data sets were included in the analysis. They had a median age of 67 years (IQR 57-75), 61% were male, and 85% presented with symptoms of heart failure according to NYHA class II or III. Pulmonary arterial hypertension (PAH, WSPH Group 1) was present in 12%, post-capillary PH (Group 2) in 54%, and chronic thromboembolic PH (Group 4) in 27% of the patients. The median value for RAP was 6 mmHg, for mPAP 26 mmHg, for pulmonary artery wedge pressure (PAWP) 13 mmHg, for cardiac output 4.8 l/min, and for pulmonary vascular resistance 2.4 WU. The median serum level of NT-proBNP was 744 pg/ml (IQR 180-1758). The ESC/ERS risk score was low in 39.8%, intermediate in 59.4%, and high in 0.8%.

NT-proBNP did not show a significant correlation with RAP but did correlate with exRAP (r=0.36, p<0.0001) and deltaRAP (r=0.37, p<0.0001), and linear regression analysis showed a significant association of deltaRAP with NT-proBNP (p=0.02). Exercise haemodynamic parameters that significantly correlated with exRAP were the ratio of increase in mPAP/cardiac output (mPAP/CO slope; r=0.39; p<0.0001), the PAWP/CO slope (r=0.37; p<0.0001), and mixed venous oxygen saturation during exercise (r=0.45; p<0.0001). Furthermore, deltaRAP was associated with the ESC/ERS risk score (intermediate and high vs. low: OR 1.1, 95%CI 1.006-1.218; p=0.04; AUC 0.60).

Conclusions: In our cohort of patients with different PH types, exercise RAP was associated with different markers of disease severity and prognosis. This innovative haemodynamic marker of right ventricular function may be used in addition to established markers to identify PH patients with an increased risk.