Effect of Time Window on Endovascular Thrombectomy with or without Intravenous Thrombolysis in Acute Ischemic Stroke: Results from DIRECT-MT

<b><i>Introduction:</i></b> Whether time window affects the intravenous thrombolysis (IVT) effect before endovascular thrombectomy (EVT) is uncertain. We aimed to investigate the effect of different time windows (0–3 h and &gt;3–4.5 h from stroke onset to randomization) on clinical outcomes of EVT with or without IVT in a subgroup analysis of DIRECT-MT. <b><i>Methods:</i></b> The primary outcome was the 90-day modified Rankin Scale (mRS) according to time window. Logistic regression models were used to analyze the effect of different treatments (EVT with or without IVT) on outcomes within 0–3 h or &gt;3–4.5 h. <b><i>Results:</i></b> Among 656 patients who were included in the analysis, 282 (43.0%) were randomized within &gt;3–4.5 h after stroke onset (125 without IVT and 157 with IVT), and 374 (57.0%) were randomized within 0–3 h (202 without IVT and 172 with IVT). We noted no significant difference in the thrombectomy-alone effect between the time window subgroups according to 90-day ordinal mRS (adjusted common odds ratio [acOR] in patients within 0–3 h: 1.06 [95% CI: 0.73–1.52], acOR in patients within &gt;3–4.5 h: 1.19 [95% CI: 0.78–1.82]) and 90-day functional independence. Thrombectomy alone resulted in an increased proportion of patients with 90-day mRS 0–3 treated within &gt;3–4.5 h (62.90 vs. 48.72%) but not within 0–3 h (65.84 vs. 63.95%). However, there was no interaction effect regarding all outcomes after the Bonferroni correction. <b><i>Conclusions:</i></b> Our results did not support thrombectomy-alone administration within 3–4.5 h in patients with acute ischemic stroke from large-vessel occlusion in the subgroup analysis of DIRECT-MT.