Objectives <p>Acute pulmonary embolism (APE) is a life-threatening condition with variable clinical outcomes. The severity of APE is typically assessed by imaging techniques like CT pulmonary angiography (CTPA). The Pulmonary Artery Obstruction Index (PAOI) is a useful tool for grading the degree of pulmonary embolism, but its impact on patient prognosis remains unclear in APE from high-altitude populations. This study aims to investigate the prognostic value of CT imaging and clinical characteristics in acute pulmonary embolism: Insights from high-altitude populations.</p> Methods <p>This retrospective study included 249 patients diagnosed with APE between January 2015 and January 2023. Patients were classified into mild (n = 104), moderate (n = 82), and severe groups (n = 63) based on their PAOI scores. All included patients received CTPA. The overall survival, clinical characteristics and CT image characteristics were analyzed using Kaplan–Meier survival curves, Cox regression models and nonlinear analysis.</p> Results <p>The study found significant differences in demographic, clinical, and radiological characteristics across the three groups. Severe group patients had higher D-Dimer levels, larger pulmonary artery diameter and larger embolism sizes. The degree of APE, embolism side, lung consolidation, pericardial effusion, and heart failure were identified as independent predictors of poor prognosis. Survival analysis revealed that embolism size (AUC = 0.697) and aortic diameter (AUC = 0.672) were moderate predictors of mortality, while pulmonary artery diameter had a low predictive value (AUC = 0.463).</p> Conclusion <p>This study demonstrates that the severity of APE, as indicated by the PAOI and radiological features such as embolism size and aortic diameter, significantly correlates with patient outcomes in high-altitude. Embolism size and aortic diameter show moderate predictive value for mortality, providing valuable insights for clinical prognosis in APE patients from high-altitude area.</p>