Floating ball thrombus in the left atrium with mitral stenosis

We report, a case of a floating ball thrombus in the left atrium with mitral stenosis in a 76-year-old woman. The patient had been followed-up at our hospital due to mitral valve stenosis for several years, and was recognized to have atrial fibrillation and a left atrial mural thrombus by echocardiography. She was admitted to our hospital for right cerebral infarction. Echocardiography showed a floating ball thrombus in the left atrium. After the treatment of cerebral infarction, she was referred to cardiac surgery, and a semi-urgent operation was performed. Removal of the ball thrombus and mitral valve replacement were performed simultaneously. The thrombus was single round, soft, relatively smooth surfaced, and about 30×30×30 mm in diameter. The postoperative course was uneventful. Left atrial ball thrombus appears to be uncommon. This is a rare case, in which it was documented that a pre-existing left atrial mural thrombus was thought to drop off spontaneously, to be a cerebral embolic source, and to develop into a ball thrombus in the left atrium.