ObjectiveTo explore the clinical application value of antithrombin Ⅲ (ATⅢ) in pulmonary thromboembolism (PTE).MethodsA retrospective study included 204 patients with confirmed PTE who were admitted to Fujian Provincial Hospital from May 2012 to June 2019. The clinical data of the study included basic conditions, morbilities, laboratory examinations and scoring system within 24 hours after admission. The relationship between ATⅢ and PTE in-hospital death was analyzed, and the value of ATⅢ to optimize risk stratification was explored.ResultsFor ATⅢ, the area under receiver operating characteristic curve (AUC) of predicting in-hospital mortality was 0.719, with a cut-off value of 77.7% (sensitivity 64.71%, specificity 80.21%). The patients were divided into ATⅢ≤77.7% group (n=48) and ATⅢ>77.7% group (n=156) according to the cut-off value, and significant statistically differences were found in chronic heart failure, white blood cells count, platelets count, alanine aminotransferase (ALT), albumin and troponin I (P<0.05). According to the in-hospital mortality, patients were divided into a death group (n=17) and a survival group (n=187), and the differences in count of white blood cells, ATⅢ, D-dimer, ALT, albumin, estimated glomerular filtration rate and APACHEⅡ were statistically significant. Logistic regression analysis revealed that ATⅢ≤77.7% and white blood cells count were independent risk factors for in-hospital death. The risk stratification and the risk stratification combined ATⅢ to predict in-hospital death were evaluated by receiver operating characteristic curve, and the AUC was 0.705 and 0.813, respectively (P<0.05). A new scoring model of risk stratification combined with ATⅢ was showed by nomogram.ConclusionsATⅢ≤77.7% is an independent risk factor for in-hospital death, and is beneficial to optimize risk stratification. The mechanism may be related to thrombosis, right ventricular dysfunction and inflammatory response.