Myxoma of the left atrial appendage mimicking thrombus during aortic valve replacement.

Echocardiographic characterization of cardiac masses involving the left atrium are defined by morphologic shape and appearance, site of attachment, type of margins, and presence or absence in the left atrial appendage. Most reports use location in the LAA as strong supportive evidence of thrombus, especially if associated with other suggestive findings (i.e., atrial fibrillation, spontaneous echo contrast, or both). Other reported masses (non-thrombi) in the left atrial appendage are considered extremely rare. We report a case of a patient with coexisting aortic stenosis and atrial fibrillation diagnosed intraoperatively by transesophageal echocardiography with myxoma of the left atrial appendage.