Alterations of right atrial (RA) function have emerged as determinants of outcome in pulmonary hypertension (PH). We aimed to clarify the pathophysiological associations of impaired RA conduit function with right ventricular (RV) function in PH. In 51 patients with PH (48 with pulmonary arterial hypertension), RA conduit function was assessed as echocardiographic peak early diastolic strain rate (PEDSR). PEDSR and cardiac magnetic resonance parameters were measured within 24 h of right heart catheterization and generation of pressure–volume loops to assess RV diastolic (RV end-diastolic pressure [EDP] and relaxation [Tau]) and systolic function. Spearman rho correlation and linear regression analysis were used to determine the association of PEDSR with RV function. The impact of PEDSR on time to clinical worsening was assessed using Kaplan–Meier and Cox regression analyses. Median (interquartile range) PEDSR was − 0.56 s − ¹ (− 1.08 to − 0.37). Impaired PEDSR was significantly correlated with RV diastolic stiffness [EDP (rho = 0.570; p < 0.001) and Tau (rho = 0.500; p < 0.001)] but not with RV contractility or coupling. In multivariate linear regression including parameters of RV lusitropic and inotropic function, EDP remained independently associated with impaired PEDSR. During a median follow-up of 9 months, 23 patients deteriorated. After multivariate adjustment, PEDSR remained associated with clinical worsening (hazard ratio: 2.85; 95% confidence interval: 1.20–6.78). Altered RV lusitropy is associated with impaired RA conduit phase. PEDSR emerged as a promising, non-invasive, bedside-ready parameter to evaluate RV diastolic function and to predict prognosis in PH.