Atrial septal defects are among the most common congenital anomalies requiring surgical repair. Thrombus formation after patch-based repair is a recognized complication, usually manifested by an embolic event. However, thromboembolic complications after primary repair of atrial septal defects are exceedingly rare. We present a 38-year-old woman found to have a right atrial mass diagnosed as a myxoma by echocardiography and magnetic resonance imaging 3 years after primary atrial septal defect repair. However, final pathology revealed an organized thrombus. A review of the literature and clinical management of postoperative atrial thrombi are discussed.
