Limited data are available on the prognostic value of haemodynamic parameters in pulmonary arterial hypertension associated to congenital heart disease (PAH-CHD). The benefit of repeated invasive hemodynamic measurements in PAH-CHD patients remains controversial. The main objective of this study was to assess the prognostic value of haemodynamic variables in PAH-CHD. This bi-centre retrospective study included 109 patients with a median age of 47 [36-38] year-old with PAH-CHD (female, 69%). A multiparametric evaluation was performed, including clinical, hemodynamical, using a robust standardized approach based on Fick principle and oxygen consumption measurement, and cardiac magnetic resonance parameters ( n = 44). Sixty-four (59%) patients had a pre-tricuspid defect. Eisenmenger syndrome was presented in 66 patients (60%). Fifty-three (49%) patients were in WHO/NYHA function class III or IV, heart rate was 80 beats.min [73–88], six-minutes walking-distance was 406 m [355–470] and oxygen saturation at rest was 91% [84–96]. Pulmonary vascular resistance (PVR) was 10 Wood Units (WU) |5–16] and mean pulmonary artery pressure (mPAP) 53 mmHg [41–69]. Eighty-four (77%) patients received PAH-specific drug therapy. Median follow-up was 17 months [10–32]. Primary outcome (death or transplantation) occurred in 29 (26%) (16 deaths, 8 underwent double-lung transplant, two cases with later atrial septal defect percutaneous closure, and 5 underwent heart-lung transplant). In multivariate analysis, right ventricular (RV) failure signs (HR 3.1; CI 95% 1.2–7.7; P = 0.01), heart rate (HR 1.1; CI 95% 1.01–1.1; P < 0.001), tricuspid annular plane excursion (TAPSE) (HR 0.84; IC 95% 0.73–0.96; P = 0.01) and PVR (HR 1.1; CI 95% 1.1–1.2; P < 0.001) remained significant predictors of death or transplantation ( Fig. 1 ). Invasive assessment of haemodynamics in patients with PAH-CHD remains the cornerstone of their prognostic assessment. PVR seems to be a strong and independent predictor of mortality and transplant in PAH-CHD patients.