A 72-year-old man presented to the emergency department because of a sudden onset of left-sidedweakness. The patient had his first cerebral vascular accident at the age of 49 years. Atrial fibrillation (AF) and hypertension were diagnosed at that time. He received warfarin with good adherence (Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack [CHADS2] score 1⁄4 3). However, the international normalized ratio was between 1.26 and 1.81 in the year before this presentation. Physical examination revealed a Glasgow Coma Score of 15, with muscle power score of 4 on the left side. Magnetic resonance imaging with gadolinium (Fig. 1A) showed an acute ischemic stroke on the right posterior parietal lobe. Transthoracic echocardiography revealed a suspected left atrial appendage (LAA) thrombus (Fig. 1B). Sixty-foureslice multidetector computed tomography (MDCT) showed 2 filling defects in the LAA. The virtual endoscopic view delineated a pedunculate thrombus (14 12 12 mm) at the body and a mural thrombus around the apex. We prescribed dabigatran 150 mg twice daily on the 15th day after the stroke. After 1 month of treatment with dabigatran, the resolution of thrombi was noted (Fig. 1, C-F). AF carries a substantial risk of stroke. Investigating the origin of thromboembolism is an important step in treating