BACKGROUNDPulmonary arterial hypertension (PAH) is a major concern in patients with Down syndrome (DS) and congenital heart disease (CHD). Understanding the unique characteristics of PAH in these populations is essential for developing tailored management strategies. This review examines differences in PAH between DS and non-DS (nDS) patients with CHD, focusing on pathophysiology, clinical presentation, hemodynamic profiles, and treatment outcomes.METHODSA retrospective analysis of 93 adults with PAH was conducted, including 18 with DS and 75 with CHD but without DS (nDS). Data on demographics, clinical presentations, comorbidities, and hemodynamic parameters were collected using echocardiography and right heart catheterization. Statistical analyses included Mann-Whitney U tests, Student's t-tests, and Kaplan-Meier survival analysis to compare the DS and nDS groups.RESULTSDS patients presented with PAH at a younger age (mean age 25.06 years) compared to nDS patients (mean age 42.4 years; p < 0.001). Hypothyroidism was more prevalent in DS patients (61.1 %) than in nDS patients (29.3 %; p = 0.012). Hemodynamic assessments showed lower mean arterial pressure (MAP) in DS patients (76.24 ± 11.6 mmHg) versus nDS patients (93.95 ± 15 mmHg; p < 0.001), and a higher TAPSE/PASP ratio (0.41 vs. 0.23; p = 0.009), suggesting less severe right ventricular dysfunction. DS patients had a significant survival advantage over nDS patients (p = 0.043).CONCLUSIONSDS patients have distinct clinical and hemodynamic profiles in PAH, requiring personalized management. Early detection and tailored treatment are crucial for improving outcomes. Further research should refine these strategies and explore new therapies.