Left Atrial Appendage Thrombosis Simulating Myxoma

A 51-year-old man was admitted to the emergency department with palpitation and atypical chest pain. He had a history of percutaneous mitral valve commissurotomy 20 years previously. He did not use any drugs. Physical examination was unremarkable except for a loud S1 on auscultation. The surface electrocardiogram (ECG) showed atrial fibrillation rhythm with rapid ventricular response and right bundle branch block. Transthoracic and transesophageal echocardiographic examinations revealed normal left ventricular size with mild systolic dysfunction, ejection fraction of 45%, and moderate rheumatic mitral stenosis with mild to moderate mitral regurgitation. Also, there was a highly mobile multilobulated mass attached to the anterior wall of the left atrial appendage with a long stalk, simulating myxoma. The patient was referred for emergent surgery, during which the mass was removed. Pathological examination demonstrated organized thrombosis. Recently, Peters and et al.1 described a woman with significant mitral stenosis and a mass in the left atrium attached to the interatrial septum through a stalk; pathological examination showed thrombosis. In another report, a man with moderate mitral stenosis and a left atrial mass attached via a narrow stalk to the interatrial septum was described.2 In cardiac magnetic resonance imaging, thrombus often appears as a hypointense structure after the administration of intravenous gadolinium, whereas atrial myxomas show contrast enhancement. This imaging modality, however, is far from perfect.3