[Mitral valve stenosis associated with a floating ball thrombus in the left atrium; report of a case].

A floating ball thrombus in the left atrium is relatively a rare case. A 70 year-old female patient who showed a symptom of heart failure was admitted to our hospital. By echocardiography, the mass in the dilated left atrium was appeared to be a floating ball thrombus, and the patient was diagnosed to be mitral valve stenosis. Following the treatment of heart failure, the patient underwent mitral valve replacement and the ball thrombus was successfully removed. Because of the high risk of sudden death with strangulated ball thrombus and systemic embolization, surgical removal of the ball thrombus should be done immediately after the diagnosis was established.