Prognostic value of follow-up hemodynamics after initial treatment in pulmonary arterial hypertension

Abstract Background Hemodynamic variables such as right atrial pressure (RAP), cardiac index (CI) and mixed venous oxygen saturation (SvO2) have consistently been associated with survival in pulmonary arterial hypertension (PAH). The prognostic importance of hemodynamics after treatment initiation seems to be superior to baseline evaluation and stroke volume index (SVI) emerged as an independent prognostic parameter. New PAH treatments are, however, able to improve exercise capacity without increasing CI or SVI. Purpose The aim of this work was to define the prognostic role of follow-up hemodynamic parameters in a population of patients with idiopathic, hereditary, drug-induced PAH (I/H/D-PAH) and PAH associated with connective tissue disease (CTD-PAH) and congenital heart disease (CHD-PAH). Methods Treatment naïve PAH patients were assessed at baseline and at 1st follow-up (3-4 months after starting PAH-specific therapy; 1st F-UP) with 6-minute walk distance (6MWD), World Health Organization functional class (WHO-FC) and right heart catheterization (RHC). Collected hemodynamic parameters were: RAP, systolic, diastolic and mean pulmonary artery pressure (s/d/mPAP), CI, SVI, SvO2, pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAC), cardiac efficiency (CE), pulmonary arterial elastance (Ea), resistance–compliance product (RC), right ventricular (RV) power, and RV stroke work index (RVSWI). The primary outcome was all cause death. We used stepwise Cox regression to assess variables obtained at baseline and at 1st F-UP. Results 794 patients with PAH were enrolled (54% I/H/D, 28% CTD, 18% CHD). A primary outcome occurred in 54% of patients over a median follow-up duration of 5.8 (2.4–11) years. In a multivariable model considering only baseline variables, no hemodynamic variables independently predicted prognosis but RAP. At first follow-up RHC (n=706), WHO-FC, 6-minute walk distance, RAP, and Ea were independently associated with death, adjusted for age, gender, and etiology of PAH. Because hemodynamic variables were highly correlated, we compared multivariable Cox regression models adding only variables with a correlation coefficient <0.6. In these models, RAP, Ea, PAC, CE, PVR, SvO2, CI, and SVI at follow-up RHC were independent predictors of death (Table). Conclusions Ea and right atrial pressure were the hemodynamic variables independently associated with death at 1st F-UP RHC after initial PAH treatment. These findings suggest that beyond improving RV function, RV afterload reduction can be considered a further treatment target.Table