Incidental Right Atrial Appendage Thrombosis in a Patient With a Left Atrial Appendage Occlusion Device

BACKGROUND: Right atrial appendage (RAA) thrombosis is exceedingly rare, is usually found incidentally on imaging, and carries a high thromboembolic risk. CASE SUMMARY: An 83-year-old man with chronic atrial fibrillation complicated by previous bleeding episodes on anticoagulation and managed most recently with a WATCHMAN device presented after a mechanical fall. Imaging work-up revealed a new incidental finding of RAA thrombosis. DISCUSSION: This case highlights an uncommon thrombotic finding and that atrial fibrillation is a biatrial disease. Occlusion of the left atrial appendage does not eliminate the risk of right-sided thrombosis. TAKE-HOME MESSAGES: Thromboembolic prevention in patients with chronic atrial fibrillation is challenging. Left atrial appendage occlusion devices, although effective, do not eliminate the risk of RAA thrombosis, as atrial fibrillation is a biatrial disease.