Abstract Number: Esoc2026a702 Cerebral Hyperperfusion Syndrome After Acute Carotid Artery Stenting During Endovascular Treatment: Two Fatal Cases

Abstract Background and aims Cerebral hyperperfusion syndrome (CHS) is a rare but severe complication after carotid revascularization.While described in elective procedures, CHS following acute carotid artery stenting (CAS) during endovascular treatment (EVT) for ischemic stroke has not been reported.We describe two patients in the CASES trial:“Carotid Artery Stenting during Endovascular treatment of acute ischemic Stroke versus deferred treatment of carotid artery stenosis” Methods We reviewed presentation, imaging, treatment, and outcome of two patients treated with immediate CAS during EVT who developed CHS. Results An 81-year-old woman with right internal carotid artery and M1 occlusion (tandem occlusion) underwent EVT with immediate CAS, achieving complete reperfusion.On day three,one day after discharge, she re-presented with severe hypertension, coma, and a right-hemispheric intraparenchymal hemorrhage. She died the next day. A 66-year-old woman with subtotal right internal carotid artery occlusion and M1 occlusion (tandem occlusion) received intravenous thrombolysis followed by EVT with immediate CAS. Four hours later, she developed hypertension, progressive hemiparesis, and generalized seizure.Computer-tomography imaging showed cerebral edema consistent with CHS.After transient improvement, she deteriorated on day 5 due to a large right-hemispheric hemorrhage and died shortly thereafter. Conclusions These two fatal cases suggest that CHS may occur after acute CAS during EVT, a setting in which it has not been previously described.Although causality cannot be proven, the temporal association strongly suggests increased vulnerability to hyperperfusion-related complications.These observations emphasize the need for structured hemodynamic monitoring and indicate the importance of the CASES trial in evaluating the safety of acute CAS during EVT. Conflict of interest Roelofs: nothing to disclose