Acute thrombus formation in the left atrium after the termination of warfarin

We report a case of acute thrombosis formation in the left atrium 3 days after the discontinuation of warfarin therapy prior to mitral valve replacement in a patient with mitral stenosis and atrial fibrillation. A 58-year-old Asian female patient was scheduled for mitral valve replacement for mitral stenosis. She had received warfarin therapy every day for 2 years. Warfarin therapy was discontinued 3 days before surgery. Using transesophageal echocardiography (TEE), we confirmed that there was no thromboembolism at the left atrium 10 days before surgery. No replacement anticoagulant therapy, such as heparin, was given after the discontinuation of warfarin. After the induction of anesthesia, a TEE probe was inserted through the esophagus to monitor left ventricular function. We found two thrombi (35 mm and 40 mm in diameter) in the left atrium. This case shows that discontinuation of warfarin therapy within a few days before operation carries a risk of thromboembolism formation.