Rare Right Atrial Thrombus Deferred Atrial Septal Defect Closure and Implantable Cardioverter-Defibrillator Placement.

A 47-year-old man with nonischemic cardiomyopathy and atrial septal defect (ASD) was scheduled for percutaneous ASD closure and to be followed by implantable cardioverter-defibrillator placement. Preprocedural transesophageal echocardiography unexpectedly revealed a large right atrial thrombus, leading to cancellation of both procedures. The patient was managed conservatively with warfarin. This case illustrates the rarity of right atrial thrombus in patients without atrial arrhythmia or indwelling devices and emphasizes the critical role of preprocedural imaging in preventing potential embolic complications. To our knowledge, this is the first reported case of a right atrial thrombus detected during ASD closure.