Serial Embolic Events From Left Atrial Appendage Thrombus Detected After Mechanical Thrombectomy: A Case Report and Management Considerations

Atrial fibrillation (AF) is a major cause of ischemic stroke, with the left atrial appendage (LAA) serving as the predominant source of thromboembolism. While the association between AF, LAA thrombus, and cerebral embolism is well established, direct visualization of an LAA thrombus in the acute post-thrombectomy setting, followed by recurrent large vessel occlusion when anticoagulation is withheld, has been only rarely documented. We report the case of an 82-year-old woman with AF on edoxaban who presented with acute right internal carotid artery (ICA) occlusion. Mechanical thrombectomy achieved successful reperfusion (TICI 2b). Subsequent imaging revealed right basal ganglia infarction with minor hemorrhagic transformation, accompanied by partial neurological recovery. Two days after onset, contrast-enhanced chest CT unexpectedly demonstrated an LAA thrombus, prompting initiation of intravenous heparin. On day 5, the patient developed sudden impaired consciousness, and MRI revealed left ICA occlusion. Repeat thrombectomy achieved partial reperfusion (TICI 2a), but follow-up imaging showed extensive left hemispheric infarction. Despite intensive treatment, she was left with severe disability (modified Rankin Scale score 5) and was transferred to a rehabilitation facility after 68 days. This case highlights the clinical importance of detecting LAA thrombus on contrast-enhanced CT after thrombectomy. Anticoagulation could not be promptly resumed due to hemorrhagic transformation, and the patient subsequently experienced recurrent embolic events. These findings underscore the need for thorough evaluation of potential embolic sources after thrombectomy, thoughtful consideration of when and how to restart anticoagulation, and the possible role of LAA occlusion as a secondary prevention strategy.