Prognostic Value of Follow–up Mean Pulmonary Arterial Pressure and Pulmonary Vascular Resistance in Patients With Pulmonary Arterial Hypertension Reaching a Low–risk Profile

Abstract Background Hemodynamic variables such as right atrial pressure, cardiac index (CI), stroke volume index (SVI), and mixed venous oxygen saturation have consistently been associated with survival in pulmonary arterial hypertension (PAH). New PAH treatments are, however, able to improve short–term outcome reducing mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) without increasing CI or SVI. The prognostic role of a mPAP 35 mmHg at follow–up and PVR values 5 WU in prevalent patients have been described. Objective The aim of this work was to define the incremental prognostic role of a mPAP 35 mmHg and PVR 5 WU in patients with idiopathic, hereditary, drug–induced PAH (I/H/D–PAH) and PAH associated with connective tissue disease (CTD–PAH) or congenital heart disease (CHD–PAH) reaching a low–risk profile at follow–up after first–line treatment strategy. Methods treatment naïve PAH patients were assessed at 1st follow–up (3–6 months after starting PAH–specific therapy; 1st F–UP) with 6–minute walk distance (6MWD), World Health Organization functional class (WHO–FC), brain natriuretic peptide (BNP)/NT–proBNP and right heart catheterization. Risk was assessed according to COMPERA 1.0, FPHR–invasive, Bologna and COMPERA 2.0 risk tools. The primary outcome was all–cause death and a combined endpoint of all cause death + need of treatment escalation. Analyses were performed using Cox regression method in patients reaching a low–risk at 1st F–UP. Data are expressed as median (IQR). Results 794 patients with PAH were enrolled (54% I/H/D, 28% CTD, 18% CHD) and 706 have a complete re–evaluation 4 (3–6) months after starting first–line treatment. Death occurred in 54% of patients over a median follow–up duration of 5.8 (2.4–11) years. Univariate analyses for all–cause death in patients reaching a low–risk profile at 1st F–UP are shown in Table 1. Univariate analyses for all cause death + need of treatment escalation, together with the initial treatment strategy and the median time from 1st F–UP to death/need of treatment escalation in patients reaching a low–risk profile at 1st F–UP are shown in Table 2. Conclusion mPAP 35 mmHg and PVR 5 WU are not of incremental prognostic value for all–cause death in patients reaching a low–risk profile at 1st F–UP after first–line treatment strategy but predict the need of future treatment escalation (after a median time 3 years).