Abstract DP276: Association Between Time to Thrombectomy and Functional Outcomes Up To 24 Hours After Last Known Well

Introduction: Endovascular thrombectomy (EVT) has proven benefit for select patients with acute stroke due to large vessel occlusion (LVO) within 24 hours of last known well (LKW). Randomized trials have shown a declining benefit of EVT within the first 6 hours, but no clear reduction in benefit after 6 hours when patients are selected by advanced imaging. We aimed to examine the association between time from LKW to EVT and outcomes in clinical practice. Methods: Using the American Heart Association/American Stroke Association Get With The Guidelines-Stroke registry data, we identified patients who underwent thrombectomy for a proximal, anterior circulation LVO at a Comprehensive or Thrombectomy-Capable Stroke Center within 24 hours of LKW. The relationships between onset (defined by LKW) to arterial puncture (OTP) time and functional outcomes at hospital discharge were quantified using generalized estimating equations adjusted for patient- and hospital-level characteristics. Results: Between January 1, 2018, and June 30, 2024, there were 41,736 patients who underwent thrombectomy within 24 hours of LKW, including 56.4% with OTP time 0–6 hours, 22.7% within 6–12 hours, 14.9% within 12–18 hours, and 6.1% within 18–24 hours. After adjustment, functional independence (defined as modified Rankin 0–2) and independent ambulation at discharge declined linearly over time (Figure 1). For each hour delay, the odds of functional independence decreased by 5.0% (95% CI, 4.4–5.5%; p<0.001) and independent ambulation decreased by 4.2% (95% CI, 3.7–4.6%; p<0.001). These associations were modified by whether symptom onset was witnessed (Figures 2 and 3). Patients with witnessed onset had an odds reduction in functional independence of 6.8% per hour (95% CI, 5.8–7.7%; p<0.001), compared to 4.1% (95% CI, 3.4–4.8%; p<0.001) with unwitnessed onset. Patients with witnessed symptom onset had 5.5% lower odds (95% CI, 4.7–6.2%; p<0.001) of independent ambulation, compared to 3.4% (95% CI, 2.8–3.9%; p<0.001) with unwitnessed onset (Figure 3). Conclusions: Earlier thrombectomy is associated with a greater likelihood of favorable outcome at hospital discharge across all timeframes, with stronger associations seen in patients with witnessed symptom onset. These results underscore the importance of reducing treatment delays to maximize the benefit of EVT in patients with LVO.