ABSTRACT
Dabigatran is a new/direct oral anticoagulant drug unlike warfarin. It is being increasingly used to prevent thromboembolism in patients with nonvalvular atrial fibrillation. We present the case of a 77-year-old woman with a giant left atrial thrombus in spite of anticoagulation therapy with dabigatran 300 mg/day. She had developed a cerebral infarction 18 months previously and was switched from warfarin to dabigatran. However, magnetic resonance imaging showed multiple new cerebral infarcts, and computed tomography scan and echocardiogram revealed a giant thrombus measuring 37×29 mm in the left atrium. Thrombectomy and left atrial appendage closure were urgently performed. Dabigatran was changed to warfarin again after the operation. She has had no recurrent thromboembolic event since then.