Abstract: AIM：To determine the relationship between the serum D-dimer level and risk of thromboembolism in patients with nonvalvular persistent atrial fibrillation. METHODS: According to results of transesophageal echocardiography (TEE) examination, 52 patients with nonvalvular persistent atrial fibrillation were divided into two groups: 1) thromboembolism (THR) group that included patients who met one or more of the following criteria: spontaneous echo contrast and/or embolism in left atrium as well as left atrial appendage-peak emptying velocity <20 cm/sec and 2) CON group. Clinical variables, transthoracic echocardiographic parameters and coagulation results were compared. Furthermore, multivariate logistic regression was performed to investigate independent risk factors for the occurrence of a thrombogenic milieu in TEE examination. RESULTS: Age, prior thromboembolism history, left atrial diameter, left ventricular ejection fraction (LVEF) and serum D-dimer in THR group were significantly different from those in CON group (P<0.05, respectively). Logistic regression analysis showed that LVEF (P<0.05) and serum D-dimer (P<0.01) were the only independent predictors of a thrombogenic milieu in TEE examination. With a threshold limit of 300 μg/L, D-dimer showed a sensitivity of 88% and a specificity of 83% in predicting elevated risks of thromboembolism in TEE examination. CONCLUSION: Similar to LVEF, D-dimer may also serve as a predictor of high risk of thromboembolism in patients with nonvavular persistent atrial fibrillation.