AimsTo clarify the prognosis and prognostic factors in pulmonary arterial hypertension (PAH) patients in real-world medical practice in the Tokai area in Japan. Main methodsWe conducted a retrospective, multicenter observational study. The data of 81 patients diagnosed with Dana Point group 1 or 1′ PAH was collected from January 2005 to January 2013. The primary outcome was all-cause death. Key findingsThe patients consisted of 34 cases of idiopathic PAH (IPAH), 28 of connective tissue-associated PAH (CTD-PAH), 16 of congenital heart disease-associated PAH (CHD-PAH) and others. Mean age was 51years and mean observation period was 46months. The systolic blood pressure (BPs) was 117±23mmHg. Pericardial effusion was observed in 27.0% of patients. The mean right atrial pressure (mRAP) was 10.2±7.3mmHg.In the univariate Cox regression analysis, WHO-FCS III & IV, a cardiac index (CI)<2.5L/min/m2, and the presence of pericardial effusion at baseline were significantly associated with all-cause death. In the multivariate analysis, the pericardial effusion (HR 3.3, 95% CI 1.03–10.63, p=0.04) and mRAP (HR 3.2, 95% CI 1.03–9.83, p=0.04) or CI<2.5L/min/m2 (HR 3.89, 95% CI 1.05–14.45, p=0.04) were the independent predictors of mortality. SignificanceThe presence of pericardial effusion and mRAP or CI<2.5L/min/m2 at diagnosis indicated high mortality.