Giant interatrial septal aneurysm mimicking a left atrial mass

Interatrial septal aneurysm (IASA) consists of redundant atrial septal tissue, which bulges into either the left or the right atrium. The clinical implications of this entity are not entirely clear; however, if it is associated with other cardiac abnormalities such as patent foramen ovale and atrial septal defects. It may assume significance by increasing the risk of cardioembolic events such as stroke. We present a case of an individual with giant IASA detected by transesophageal echocardiography, which was mimicking a left atrial mass on transthoracic echocardiography. This case emphasizes the superiority of transesophageal imaging over transthoracic echocardiography for this clinical entity.