Giant left atrial ball thrombus in a patient with chronic nonvalvular atrial fibrillation.

A 56-year-old woman with chronic nonvalvular atrial fibrillation presented with cardiac arrest during magnetic resonance imaging for back pain evaluation. Brain magnetic resonance imaging performed after cardiopulmonary resuscitation revealed multiple embolic lesions. Transesophageal echocardiography showed a large free floating thrombus ball and multiple mural thrombi in the left atrium. In light of the high-risk situation, an emergency operation was performed despite the occurrence of a fresh stroke within the previous 24 hours. The surgery was successful and the postoperative course was uneventful. The patient has been doing well since the operation on outpatient follow-up for 8 months.