Inverted left atrial appendage developing after mitral valve replacement surgery

An inverted left atrial appendage (ILAA) is a rare occurrence after cardiac surgery and can be misinterpreted as a left atrial thrombus, mass, or vegetation. Transesophageal echocardiography (TEE) used post-operatively is useful in detailed visualization of the left atrium and any abnormality within it. We present a case in which a patient developed an ILAA post mitral valve replacement (MVR) and was diagnosed using TEE. We want to emphasize the importance of TEE post-operatively and that differentials for a left atrial mass must include ILAA, especially after cardiac surgery. This can help in preventing unnecessary anticoagulation and the need for surgical revision.