Suspected intraoperative formation of left atrial thrombus in a patient with atrial fibrillation receiving bridging anticoagulation therapy.

We present a patient with atrial fibrillation (AF) in whom a left atrial (LA) thrombus might have formed during laparotomy despite bridging anticoagulation therapy. No evidence of thrombus was detected by transesophageal echocardiography (TEE) at the start of surgery; however, a thrombus measuring 13 × 10 mm was found in the LA appendage by the end of the procedure, suggesting that thrombus might develop intraoperatively in patients with AF even when bridging anticoagulation is properly established. Intraoperative TEE can assist in detecting intracardiac thrombus in patients with AF regardless of their anticoagulation status and provides a tool for intervention to prevent systemic embolization.