Objective To achieve clinical grouping of patients with atrial septal defects and pulmonary hypertension to reflect prognostic differences by using cluster analysis. Methods Patients diagnosed with atrial septal defect and mean pulmonary artery pressure > 20 mmHg in Guangdong Provincial People's Hospital between November 2020 and December 2023 were enrolled. Baseline clinical data were collected. Two-stage cluster analysis was performed to generate patient subgroups. Clinical parameters among subgroups was analyzed. Prognostic outcomes were compared by using survival analysis. Results Four subgroups with favorable clustering performance were identified. Clustering effect was good ( Wilks' lambda = 0. 011, P = 0. 001) . Patients in the subgroup 1 had mild pulmonary hypertension and significantly deteriorated right ventricular function. Patients in the subgroup 2 had mild pulmonary hypertension and compensated right ventricular function. Patients in the subgroup 3 had the lowest degree of pulmonary hypertension with compensated right ventricular function. Patients in the subgroup 4 had significantly elevatory pulmonary hypertension and significantly deteriorated right ventricular function. In the subgroup 4, patients had significantly elevated mean pulmonary artery pressure and pulmonary vascular resistance. Their right ventricular area change fraction was significantly decreased ( P < 0. 05) . Their left ventricular eccentricity index was significantly abnormal ( P<0. 05) . In the subgroup 1, patients showed relatively specific etiology with comorbid left heart-related diseases. Their cardiac function was significantly deteriorated ( P < 0. 05) . Their right heart was significantly enlarged ( P<0. 05) . The right ventricular structural and functional indicators of patients in the subgroup 2 and the subgroup 3 were superior to those of the subgroup 1 and the subgroup 4. After a median follow-up of 35 months, a total of 25 adverse events occurred. The incidence of adverse events in the subgroup 4 was higher than that in the other subgroups. The subgroup 2 and the subgroup 3 had favorable prognoses, but there was no statistically significant difference between the two subgroups. Cox regression analysis with subgroup 4 as a reference showed that the risk of adverse events in subgroup 3 was significantly lower than that in subgroup 4 ( HR = 0. 20, 95% CI: 0. 07 ~ 0. 62, P < 0. 05) . Conclusions Patients with atrial septal defects and pulmonary hypertension still have a significant heterogeneity. Echocardiographic parameters of right ventricular function have considerable potential for assessing the condition of patients with pulmonary hypertension.