Science and Education Publishing American Journal of Medical Case Reports 2374-216X 4 3 2016 4 18 Huge Interatrial Septum Aneurysm 111 114 EN Pramod Theetha Kariyanna Department of Internal Medicine, State University of new York, Downstate Medical Center, U.S.A. Apoorva Jayarangaiah Robert Adrah Abhishek Sharma AJMCR20164310 10.12691/ajmcr-4-3-10 2015 11 30 2016 2 5 2016 4 16 Atrial septum aneurysm (ASA) is a saccular aneurysm of the interatrial septum, bulging into either atrium during the cardiac cycle. It is mostly congenital in natures and is often associated with patent foramen ovale (PFO). ASA is increasingly gaining attention as a possible cause of cryptogenic stroke. We here present a case of ASA in an elderly female in whom ASA possibly contributed to atrial fibrillation and mitral valvular prolapse; she denied any thromboembolic event. Transesophageal echocardiography remains the imaging modality of choice for diagnosis of ASA. Management guidelines for initiation of antiplatelet therapy, anticoagulation and the need for endovascular or surgical closure of associated PFO are lacking.