A modified 4-strata risk assessment incorporating TAPSE/sPAP for pulmonary arterial hypertension: evidence from a large chinese real-world cohort

Background Pulmonary arterial hypertension (PAH) is a progressive disease with poor prognosis. The 2022 ESC/ERS guidelines recommend the 4-strata risk model based on WHO functional class (WHO-FC), N-terminal pro-brain natriuretic peptide (NT-proBNP) and 6-minute walk distance (6MWD) to assess one-year mortality risk and guide treatment decisions at follow-up. However, in routine practice in China, 6MWD is frequently unavailable. The tricuspid annular plane systolic excursion/systolic pulmonary artery pressure (TAPSE/sPAP) ratio, an echocardiographic marker of right ventricular–pulmonary artery coupling with established prognostic value is routinely assessed in PH centers and may offer a practical alternative for follow-up risk assessment. Purpose To develop and internally validate a modified 4-strata risk assessment model incorporating TASPE/sPAP as a practical alternative to 6MWD for follow-up risk stratification in PAH. Methods This single-center retrospective cohort study included treatment-naïve, newly diagnosed PAH patients who underwent right heart catheterization and had follow-up assessment with either 6MWD or echocardiography at a cardiovascular disease specialized hospital between 1 January 2018 and 30 November 2024. The cohort was randomly divided into training and test sets (70%:30%). WHO-FC and NT-proBNP were scored according to 2022 ESC/ERS 4-strata risk tool. Intermediate-low- and intermediate-high-risk TAPSE/sPAP cut-offs were derived from multivariable Cox regression optimized for 1-, 2-, and 3-year mortality, while low- and high-risk thresholds followed ESC guidelines. Model discrimination was assessed using the C-index and time-dependent AUC. Changes in risk strata from baseline to first follow-up were also evaluated. Results Among 12,858 screened patients, 769 were eligible and 542 with TAPSE/sPAP follow-up were analyzed (mean age 36.1 ± 11.8 years; 78.8% female). A modified 4-strata model integrating WHO FC, NT-proBNP, and TAPSE/sPAP was developed. The model showed good discrimination, with C-indices of 0.79 (training) and 0.72 (test). Two- and three-year AUCs were 0.82 and 0.83 in the training set, and 0.74 and 0.73 in the test set. The optimal TAPSE/sPAP cut-off was 0.26, and thresholds defining 4-strata were 0.19, 0.26, and 0.32. An univariable TAPSE/sPAP model remained robust (C-index 0.71). Five-year survival rates were 97.4%, 87.4%, 67.6%, and 27.8% from low to high risk (P<0.001). The model further discriminated prognosis within intermediate-risk patients, particularly for long-term outcome. Risk distribution shifted from 22.0%, 40.6%, 26.2%, and 11.2% at baseline to 40.8%, 35.8%, 17.0%, and 6.4% at follow-up. Conclusion A modified 4-strata model incorporating TAPSE/sPAP provides good discrimination for follow-up risk stratification in a real-world Chinese PAH cohort and may serve as a practical alternative when 6MWD is unavailable.