Left atrial thrombus and prognosis after anticoagulation therapy in patients with atrial fibrillation.

BACKGROUND: Anticoagulation therapy reduces the risk of thromboembolic events by two-thirds in patients with atrial fibrillation (AF). The prevalence of left atrial thrombus (LAT) in AF patients with anticoagulation therapy has not been fully investigated. PURPOSE: To investigate the prevalence of LAT and its impact on the outcomes in patients with nonvalvular AF after anticoagulation therapy. METHODS: This study consisted of 231 patients with nonvalvular AF who had transthoracic (TTE) and transesophageal echocardiographic (TEE) examinations more than 3 weeks after anticoagulation therapy. The clinical and echocardiographic characteristics were evaluated. RESULTS: LAT was observed in 13 (8.8%) of 148 patients with sub-therapeutic anticoagulation, and in 3 (3.6%) of 83 patients with sufficient anticoagulation. The presence of LAT was associated with higher CHADS(2) score, decreased LA volume changes and the presence of spontaneous echocardiographic contrast (SEC) in patients with sub-therapeutic anticoagulation. Patients with LAT after sufficient anticoagulation were male with permanent AF who had decreased left ventricular systolic and diastolic function and dilated LA on TTE and SEC, and reduced appendage flow velocity on TEE. Patients with LAT had worse cardiovascular outcomes compared with those without LAT (p=0.02). CONCLUSIONS: We demonstrated that LAT was a univariate risk factor associated with worse cardiovascular outcomes, which was observed in 8.8% of patients with sub-therapeutic anticoagulation and 3.6% of patients with sufficient anticoagulation.