Endovascular Rescue for Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage - a Meta-Analysis

IntroductionEndovascular rescue treatment, including intra-arterial spasmolysis and/or transluminal balloon angioplasty, is widely used for symptomatic vasospasm and delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH), yet its impact on functional recovery remains uncertain. We systematically reviewed and synthesized the evidence on patient-centered outcomes, exploring effects by follow-up time, intervention type, and clinical severity. Materials and methodsFollowing a prospectively registered protocol (Research Registry: reviewregistry1466) and PRISMA guidance, we searched PubMed, EMBASE, and Web of Science (January 2000-December 2024; final update July 2025). Prospective and retrospective studies of adult aSAH patients receiving endovascular treatment for symptomatic angiographic vasospasm were included. Data extraction followed a standardized PICO framework, and study quality was assessed using the Newcastle-Ottawa Scale. Because reporting of angiographic resolution and DCI-related infarction was sparse or inconsistent, quantitative synthesis focused on dichotomized favorable functional outcome (e.g., mRS 0-2 or GOS good recovery). Single-arm meta-analyses of proportions were performed on the logit scale using random-effects generalized linear mixed models, with subgrouping by follow-up, intervention, and clinical severity. ResultsThirty-nine studies (1,627 patients; 27 retrospective cohorts, 5 prospective cohorts, 5 case series, 2 randomized trials) met inclusion criteria; 38 contributed to meta-analysis. The pooled proportion of favorable functional outcomes was 0.55 (95% CI, 0.50-0.61) with substantial heterogeneity (I{superscript 2} {approx} 71%). Prespecified subgroup analyses by follow-up duration, intervention type, and baseline severity did not reveal significant differences. The two randomized trials reported conflicting short-term results with limited follow-up. Safety reporting was variable but generally acceptable for pharmacologic spasmolysis, while higher complication rates were occasionally observed with mechanical interventions. ConclusionAmong patients with symptomatic vasospasm or DCI requiring endovascular rescue, approximately half achieve a favorable functional outcome. However, marked heterogeneity and reliance on predominantly observational data preclude firm conclusions regarding comparative effectiveness. Standardized multicenter randomized trials with harmonized definitions of eligibility, timing, outcomes, and adverse events are needed to clarify the therapeutic role and optimize patient selection for endovascular rescue after aSAH.