Left atrial thrombus in a patient without mitral valve disease or atrial fibrillation.

A 54-year-old man presented with back pain. His medical history included hypertension and gout. There was no history of heart disease or arrhythmia. The electrocardiogram showed normal sinus rhythm. Chest computed tomography demonstrated a large calcified tumor (65 mm) in the left atrium (LA). The echocardiogram showed a round hyperechoic mass in the enlarged LA (56 mm) attached to the atrial septum without mitral valve disease. Urgent surgery for excision of the LA mass with the atrial septum and reconstruction by autologous pericardial patch was performed. There was no pathological change in the mitral valve. Due to surgical injury to the conduction system, implantation of a permanent pacemaker was required postoperatively. Histopathological examination revealed calcification, fibrosis, and thrombus formation. LA thrombus without any history of mitral valve disease or atrial fibrillation is rare. Although the mechanism of the present case was unclear, extensive calcified LA myxoma or undiagnosed patent foramen ovale might have been associated with the disease. <Learning objective: A smooth surface, floating left atrial "ball thrombus" occurs rarely in patients with mitral valve disease or atrial fibrillation. We present a rare case of a giant round left atrial thrombus in a patient without any history of mitral valve disease or atrial fibrillation. Transesophageal echocardiogram showed that the thrombus was round, fixed to the septum, and not floating, and that its surface was calcified. This disease in this patient might have been associated with extensive calcified left atrial myxoma, paroxysmal atrial fibrillation, or undiagnosed patent foramen ovale.>.