Intraoperative Heparin Resistance and Internal Carotid Artery Occlusion After Andexanet Alfa Reversal During Endovascular Treatment of a Ruptured Cerebral Aneurysm: A Case Report

A 56-year-old woman receiving oral edoxaban (30 mg/day) was transferred to our hospital with impaired consciousness and headache. Head computed tomography revealed a subarachnoid hemorrhage and a 7-mm aneurysm located at the junction of the left internal carotid artery-posterior communicating artery. Andexanet alfa was administered 11.5 hours after the patient's last dose of edoxaban to reduce the potential rebleeding risk before aneurysm treatment. During coil embolization, acute occlusion of the left internal carotid artery was observed. Mechanical thrombectomy was subsequently performed, achieving successful reperfusion. Postoperative magnetic resonance imaging revealed an acute cerebral infarction in the watershed areas. The patient was discharged 48 days after onset with a modified Rankin Scale score of 0. Although impaired anticoagulation response and thrombotic events have been reported following andexanet alfa administration, acute large-vessel occlusion can also occur in this setting. Careful consideration of risk-benefit balance is warranted when performing neuroendovascular procedures requiring systemic heparinization.