In acute ischemic stroke, a longer time from onset to endovascular treatment (EVT) is associated with worse clinical outcome. We investigated the association of clinical outcome with time from last known well to arrival at the EVT hospital and time from hospital arrival to arterial access for anterior circulation large vessel occlusion patients treated > 6 hours from last known well.

Retrospective analysis of the prospective, multicenter cohort study ESCAPE-LATE. Patients presenting > 6 hours after last known well with anterior circulation large vessel occlusion undergoing EVT were included. The primary outcome was the modified Rankin Scale (mRS) score at 90 days. Secondary outcomes were good (mRS 0–2) and poor clinical outcomes (mRS 5–6) at 90 days, as well as the National Institutes of Health Stroke Scale at 24 hours. Associations of time intervals with outcomes were assessed with univariable and multivariable logistic regression.

Two hundred patients were included in the analysis, of whom 85 (43%) were female. 90-day mRS was available for 141 patients. Of the 150 patients, 135 (90%) had moderate-to-good collaterals, and the median Alberta Stroke Program Early CT Score (ASPECTS) was 8 (IQR = 7–10). No association between ordinal mRS and time from last known well to arrival at the EVT hospital (odds ratio [OR] = 1.01, 95% CI = 1.00–1.02) or time from hospital arrival to arterial access (OR = -0.01, 95% CI = -0.02–0.00) was seen in adjusted regression models.

No relationship was observed between pre-hospital or in-hospital workflow times and clinical outcomes. Baseline ASPECTS and collateral status were favorable in the majority of patients, suggesting that physicians may have chosen to predominantly treat slow progressors in the late time window, in whom prolonged workflow times have less impact on outcomes.