Siblings with Idiopathic Left Atrial Appendage Ostial Stenosis and Cor Triatriatum.

Isolated left atrial appendage (LAA) ostial stenosis is a very rare entity found coincidentally in adults by transesophageal echocardiography. A 3-month-old healthy infant was suspected as having cor triatriatum. His brother had a history of surgical treatment of cor triatriatum. A cardiac catheterization revealed a narrowed ostium of the LAA and confirmed the echocardiographic diagnosis of isolated LAA ostial stenosis. This is the first pediatric case of idiopathic LAA ostial stenosis. The siblings called our attention to the differential diagnosis and the etiopathogenesis between LAA ostial stenosis and cor triatriatum.