Association Between Time to Treatment and Outcomes of Endovascular Therapy vs Medical Management in Patients With Large Ischemic Stroke.

Background and objectives: Randomized trials have proven the benefit of endovascular therapy (EVT) for acute large ischemic stroke. This study was to characterize the effect of time to treatment on benefit of EVT vs medical management (MM) among patients with large ischemic stroke.

Methods: This was a post hoc analysis of the Endovascular Therapy in Acute Anterior Circulation Large Vessel Occlusive Patients with a Large Infarct Core randomized trial. Patients who had an Alberta Stroke Program Early Computed Tomography Score of 3-5 or an ischemic core volume of 70-100 mL within 24 hours of symptom onset were treated with EVT plus MM or MM. Onset-to-expected arterial puncture time (OPT) was analyzed as a categorical variable (<6, 6-<12, and 12-24 hours) using binary logistic regression and as a continuous variable using a multivariable fractional polynomial interaction. The primary efficacy outcome was favorable outcomes (modified Rankin Scale scores 0-3) at 90 days. Safety outcomes included any intracranial hemorrhage (ICH), symptomatic ICH, and mortality.

Results: Among 451 patients (median age 68 years; 61.4% were men; median OPT 487 minutes [interquartile range 328-802]), 226 patients received EVT and 225 patients received MM. The EVT group showed higher rates of favorable outcomes than the MM group within OPT of 6 hours (44.4% vs 29.9%, adjusted odds ratio [aOR] 2.78, 95% CI 1.22-6.32) and 6-12 hours (45.7% vs 29.6%, aOR 2.39 [95% CI 1.21-4.71]), but not in OPT beyond 12 hours (51.6% vs 41.4%, aOR 2.05 [95% CI 0.88-4.77]). The benefit became nonsignificant after OPT of 13 hours and 22 minutes. In 3 OPT intervals, the rates of symptomatic ICH and mortality were similar between EVT and MM although the rate of any ICH increased. However, no interaction effect was found (all p interactions >0.10).

Discussion: These findings strengthen the benefit of EVT initiated within 13 hours and 22 minutes after symptom onset compared with MM alone in patients with large ischemic stroke, but EVT should not be withheld for patients presenting beyond 13 hours and 22 minutes. Pooled analysis of larger sample sizes is needed.

Trial registration information: ClinicalTrials.gov; NCT04551664.

Classification of evidence: This study provides Class II evidence that EVT is associated with improved functional outcomes for acute large ischemic stroke within 24 hours after last known well, with no interaction by time.