Highly mobile pedunculated left atrial appendage thrombus falling into the mitral valve orifice.

We treated two patients with atrial fibrillation and stringlike left atrial appendage thrombus: a 66 year-old man who had apical hypertrophic cardiomyopathy and a 86 year-old woman with no underlying heart disease. In the patient with hypertrophic cardiomyopathy, transesophageal echocardiography showed a highly mobile stringlike echo protruding from the left atrial appendage and sometimes falling into the mitral orifice. Pathologic examination after excision proved the stringlike echo to be a pedunculated structure composed of red and white thrombi. Excision of thrombus was also planned for the woman, who had a history of recurrent cerebral embolism. Because her cerebral CT showed infarction with bleeding, however, surgery was postponed. The stringlike mobile thrombus was not detected by transesophageal echocardiography 1 month later, when a new embolic episode affected a foot. Clinical outcomes of these two patients differed remarkably. The critical findings by transesophageal echocardiography which facilitated differential diagnosis from cardiac tumors were: spontaneous contrast echo accompanying mural thrombuslike echo, and low flow velocity in the left atrial appendage. However, the differential diagnosis may be quite difficult in cases of tumors associated with atrial fibrillation.