Exclusion of Intra-Atrial Thrombus Diagnosis Using D-Dimer Assay Before Catheter Ablation of Atrial Fibrillation

OBJECTIVES This study hypothesized that the association of D-dimer blood level and several clinical items in a new risk score could predict the absence of atrial thrombus. BACKGROUND Symptomatic and drug resistant atrial fibrillation (AF) can be treated by catheter ablation. The procedure-related risk of thromboembolism is limited by the pre-operative use of transesophageal echocardiography (TEE) to detect atrial thrombi. METHODS Patients admitted for catheter ablation of AF (n = 2,494) were prospectively included in a multicenter study. TEE was systematically performed before the procedure to search for atrial thrombus (primary endpoint). D-dimer level, CHADS2 score, left ventricular ejection fraction, pre-operative anticoagulation regimen, and medical history were collected. A logistic regression model was used to identify factors associated with the presence of atrial thrombus (hypertension, history of stroke, heart failure, D-dimer level >270 ng/ml). These factors were aggregated in a new score called atrial thrombus exclusion (ATE). RESULTS The incidence of atrial thrombus was 1.92%. CHADS2 score and D-dimer level were significantly associated with atrial thrombus (p < 0.0001 and p < 0.0001, respectively). A zero CHADS2 score failed to exclude all atrial thrombi (5 false negatives; sensitivity: 89.58%, specificity: 52.2%). No false negative was found with a zero ATE score, which had a specificity of 37% and a higher sensitivity (100%) than the CHADS2 score (p < 0.031) to predict the absence of intraatrial thrombi on TEE. Conversely, the positive predictive value was poor, and the ATE score should not be used to conclude a positive diagnosis of thrombus. CONCLUSIONS An ATE score of zero was strongly associated with the absence of atrial thrombus. This new score could be useful to rule out a diagnosis of atrial thrombus before catheter ablation of AF.