Simultaneous Left and Right Atrial Appendage Thrombi on Cardiac Computed Tomography

We report an unusual case of simultaneous left and right atrial appendage thrombosis identified on contrast-enhanced cardiac computed tomography angiography (CT) during pre-procedural evaluation in a patient with permanent atrial fibrillation and structural heart disease. Cardiac CT demonstrated well-defined filling defects within both atrial appendages on arterial and delayed phases, consistent with intracavitary thrombi. The patient was already receiving long-term oral anticoagulation for atrial fibrillation. In this case, antithrombotic management was not modified after multidisciplinary clinical assessment, as the patient remained asymptomatic and at high bleeding risk. This case highlights the diagnostic value of multiphasic cardiac CT in pre-procedural imaging, and underscores that systematic bilateral appendage assessment is essential, as right atrial appendage thrombus may otherwise go undetected.