Abstract

We report a case of a 63-year-old man without a history of atrial fibrillation or mitral valve disease who was admitted to our hospital. Echocardiography revealed a large left atrial mass attached to the atrial septum. We suspected the mass to be a myxoma, but it turned out to be a large thrombus after the surgery. Left atrial thrombus without mitral valve disease or atrial fibrillation is rare. Although the degree of urgency varies based on the case, early surgical resection is recommended for a large left atrial thrombus to prevent embolism.