Characteristics of non-valvular atrial fibrillation with left atrial appendage thrombus who are undergoing appropriate oral anticoagulation therapy

We investigated the characteristics of patients with non-valvular atrial fibrillation (NVAF) and left atrial (LA) appendage (LAA) thrombus who had been given appropriate oral anticoagulation therapy. We studied 737 NVAF patients who were scheduled for catheter ablation or electrical cardioversion. All patients received appropriate oral anticoagulation therapy for at least 3 weeks prior to echocardiography in accordance with the guidelines. Whether LAA thrombus was present or absent on transesophageal echocardiography (TEE) was determined by at least three senior echocardiologists. LAA thrombi were observed in 22 patients (3.0%). Multivariate logistic regression analysis showed that LAA flow and LA volume index were both independent predictors of LAA thrombus formation; however, LAA flow (<= 18 cm/s) was indicated as a more powerful predictor. Moreover, the prevalence of LAA thrombus formation in patients with NVAF without LA enlargement (LA volume index <= 34 mL/m(2)) was extremely rare (0.4%). LAA thrombus formation in patients with a mildly dilated LA volume index of 34-49.9 mL/m(2) and paroxysmal AF was also extremely rare (0.0%). LAA flow is strongly associated with LAA thrombus formation, even in NVAF patients treated with appropriate oral anticoagulation therapy. Augmented oral anticoagulation therapy or transcatheter or surgical LAA closure should be considered for such patients, especially for those with an LAA flow < 18 cm/s. Furthermore, TEE for evaluating LAA thrombus before catheter ablation or electrical cardioversion may be unnecessary for NVAF patients who are undergoing appropriate oral anticoagulation therapy, depending on LA size.