CONGRESS ABSTRACT

Background: Hemodynamic variables related to right ventricular (RV) function have consistently been associated with survival in pulmonary arterial hypertension (PAH). New PAH treatments, however, seems to improve RV coupling reducing RV afterload [e.g. mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR)], but without increasing cardiac output. 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 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) at follow-up after first-line treatment strategy. Methods: treatment naüve PAH patients were assessed at 1st follow-up (3-6 months after starting PAH-specific therapy; 1st F-UP) with right heart catheterization. The primary outcome was all-cause death. Analyses were performed using Kaplan Meier curves and comparisons were done with Log-rank test. Cox regression analysis was used to find the predictive value of mPAP and PVR at bivariate analysis. 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. Survival curves according to a cut-off value of 35 mmHg for mPAP and 5 WU for PVR are shown in the Figure. Patients with PVR <5 WU and mPAP <35 mmHg have a better prognosis than patients with PVR ≥5 WU (independently from mPAP; p-values <0.02) but have the same prognosis of patients with PVR <5 WU and mPAP >35 mmHg (p-value= 0.666). Patients with PVR <5 WU and mPAP >35 mmHg have a better prognosis than patients with PVR ≥5 WU and mPAP >35 mmHg (p-value= 0.031) and a trend toward a better prognosis than patients with PVR ≥5 WU and mPAP <35 mmHg (p-value= 0.06). Patients with PVR ≥5 WU have the same prognosis independently from mPAP (p-value= 0.683). In a bivariate Cox regression analysis only PVR <5 WU predict prognosis [HR (95%CI)= 0.61 (0.44-0.84); p-value= 0.002] while a mPAP <35 ​​mmHg is not prognostic [HR (95%CI)= 1.00 (0.72-1.40); p-value= 0.991]. Conclusions: mPAP <35 ​​mmHg does not further discriminate the survival over a cut-off value of 5 WU of PVR.