Flow diversion for intracranial aneurysms in patients with sickle cell disease

Introduction: Sickle cell disease (SCD) confers a three-to fivefold increase in the prevalence of intracranial aneurysms (IA). Flow diversion (FD) requires mandatory dual antiplatelet therapy (DAPT), yet perioperative transfusion to reduce hemoglobin S (HbS) risks delayed hemolytic transfusion reaction (DHTR). No guidelines address this conflict between DHTR-associated coagulopathy and mandatory DAPT. We report the largest FD series in SCD. Methods: Retrospective single-center case series of SCD patients undergoing FD for IA (2017 to 2026). Of 12 SCD patients treated for aneurysms, seven received FD and comprised the analytic cohort. Results: Seven patients (5 HbSS, 2 HbS/β⁰-thalassemia; median age 38; 71% female) harbored 29 aneurysms; 12 were treated with FD across 8 procedures using 15 devices. HbS <30% was achieved in 3 of 7 (43%); one patient underwent FD at HbS 78.5% due to alloimmunization. Clopidogrel hyporesponsiveness was identified in 2 of 4 TEG-tested patients (50%). Procedure-related mortality was 14% (1/7): fatal DHTR with DIC on postoperative day 8, the first reported DHTR-DAPT collision. Procedure-related morbidity included one intraoperative thrombus and one vasospasm episode, both resolved without sequelae (2/8 procedures, 25%). Additional events included asymptomatic in-stent stenosis and delayed stroke from SCD vasculopathy. At last follow-up, 5 of 6 survivors maintained mRS 0 to 1. Discussion and Conclusion: FD is technically feasible in SCD, but the 14% procedure-related mortality from a fatal DHTR exposes the unresolved conflict between transfusion-associated hyperhemolysis and mandatory DAPT. CYP2C19-mediated clopidogrel resistance and alloimmunization pose additional challenges that require predefined protocols and prospective multicenter registries.