The Role of Anticoagulants After Left Atrial Appendage Occlusion

Left atrial appendage occlusion prevents thromboembolic events in atrial fibrillation patients with bleeding risk, but device-related thrombosis (DRT) remains a challenge.

A 78-year-old man with atrial fibrillation (CHA₂DS₂-VASc score = 3) and prior intracranial hemorrhage underwent successful left atrial appendage occlusion with a 22-mm Amplatzer Amulet. After stepping down from apixaban to aspirin, DRT developed. Thrombi resolved with apixaban but recurred on its discontinuation. A multiscale model integrating hemodynamics, thrombus formation events, and apixaban revealed fibrin buildup beneath the pulmonary ridge, matching clinical thrombus. Optimized placement alone prevented fibrin formation in the virtual model.

Pulmonary ridge coverage and low-dose direct oral anticoagulants have emerged as effective strategies to reduce DRT. This case links both mechanisms, showing recurrence due to incomplete ridge coverage and antithrombotic decision.

Our high-fidelity model offers mechanistic insight about antithrombotic therapy, which cannot be assessed with flow-based simulations alone. The results presented provide proof-of-concept evidence of the model's capabilities.