Impact of time to endovascular securement on outcomes in aneurysmal subarachnoid hemorrhage

Guidelines recommend aneurysm securement within 24 h from arrival for aneurysmal subarachnoid hemorrhage (aSAH) but the optimal treatment window within this timeframe remains unclear. We examined the association between arrival-to-treatment (AtT) timing and outcomes in patients undergoing endovascular securement for aSAH.

We retrospectively analyzed a prospectively collected cohort of patients with aSAH treated at a single academic center between 2015-2023. Multivariate logistic regressions (MLR) and multivariate generalized additive models (MGAM) evaluated the relationships between AtT time and outcomes including poor functional outcome at 3 months (modified Rankin scale [mRS] 3-6), primary outcome) and unfavorable discharge disposition (secondary outcome). Subgroup analyses were performed for patients with Hunt and Hess (HH) grades ≥ 3. We also analyzed AtT time in relation to preprocedural aneurysmal rebleeding.

Of 434 patients with aSAH reviewed, 351 underwent endovascular treatment (mean age, 57.7 ± 13.7; 64.1% female; 94.3% treated within 24 h). For the overall cohort, AtT time was not significantly associated with poor functional outcome (MLR: OR 0.67, 95%CI [0.44, 1.05], p = 0.08; MGAM: edf = 1, p = 0.06). Among high HH-grade patients, longer AtT time was associated with improved outcomes (MLR: OR 0.54, 95%CI [0.32, 0.91], p = 0.024; MGAM: edf = 1, p = 0.02). Longer AtT was not associated with increased preprocedural rebleeding (MLR: OR 1.37, 95%CI [0.66, 3.15] p = 0.4).

In high-grade aSAH, modest variation in arrival-to-treatment time within the AHA-recommended 24-hour window was not associated with worse outcomes and was associated with improved functional recovery. However, this finding is likely influenced by clinician triage patterns, survival bias, and residual confounding rather than a causal benefit of delayed intervention. These results reinforce the safety of early aneurysm treatment within established guidelines while highlighting the complex interplay between patient stability, procedural timing, and institutional workflow. Larger prospective multicenter studies are needed to clarify optimal timing across diverse practice settings.