Supramitral membrane with left atrial appendage thrombus: A rare entity.

A 4-year-old child with supramitral membrane (SMM) causing severe mitral stenosis (MS) was taken for excision of the membrane. Intraoperative transesophageal echocardiography showed a large thrombus in the left atrial appendage (LAA) in addition to SMM. The case underscores the importance of this extremely rare association and prompt therapy to prevent catastrophic consequences.