OBJECTIVE. The purpose of this study is to assess CT-based markers predictive of the development of chronic thromboembolic pulmonary hypertension (CTEPH) after acute pulmonary embolism. MATERIALS AND METHODS. Identified from a search of local registries, 48 patients who had CTEPH develop were included in the study group, and 113 patients who had complete resolution of acute pulmonary embolism were included in the control group. Baseline CT scans obtained at the time of the initial pulmonary embolism event were evaluated for the degree of clot-induced vessel obstruction, the quantitative Walsh score, the ratio of the right ventricle diameter to the left ventricle diameter, the right atrium diameter, the pulmonary artery diameter, right heart thrombus, pericardial effusion, lung infarction, and mosaic attenuation. Classification and regression tree analysis was used to create a decision tree. The decision tree was externally validated on an anonymized cohort of 50 control subjects and 50 patients with CTEPH. RESULTS. During univariable analysis, an increase in the degree occlusive clot on initial imaging, a decrease in the Walsh score, absence of pericardial effusion, presence of lung infarction, and the presence of mosaic attenuation were associated with an increased probability of CTEPH development. In the final decision tree, the occlusive nature of the clot remained. Two patients in the cohort used for external validation had nondiagnostic findings and were excluded. The decision process correctly classified 33% (16/48) of patients who had CTEPH develop and 86% (43/50) of patients who did not have CTEPH develop, for an odds ratio of 3.1 (95% CI, 1.1-8.3). CONCLUSION. The presence of an occlusive clot on initial imaging is associated with an increased probability of CTEPH development. Presence of mosaic attenuation and lung infarction may also predict CTEPH development, although additional studies are needed.