A number of multicenter randomized controlled trials have provided evidence supporting the application of endovascular therapy for acute ischemic stroke with anterior circulation large vessel occlusion. However, whether intravenous thrombolysis is necessary before endovascular therapy is still controversial. The combined trial data (including DEVT, DIRECT-MT, MR-CLEAN NO-IV and SKIP) assessing direct mechanical thrombectomy versus bridging therapy showed no difference in improving good functional outcome. However, a recent observational cohort study of 15832 patients treated with EVT, intravenous alteplase treatment was associated with better in-hospital survival and functional outcomes after adjusting for other covariates.~The 2019 AHA/ASA guidelines for the early management of patients with ischemic stroke states that mechanical thrombectomy is recommended for patients with anterior circulation large vessel occlusion within 6-24 hours of last known normal who meet the DWAN or DEFUSE-3 criteria (level I recommendation, level A evidence). The DEFUSE 3 perfusion-infarction core mismatch criteria is: core infarct volume <70mL, ischemic penumbra volume >15mL, and hypoperfusion volume/core infarct volume >1.8. Intravenous thrombolytic therapy is recommended for patients with ischemic stroke within 4.5 hours of onset. A meta-analysis of three randomized controlled trials recently published in the Lancet found that ischemic stroke at 4.5 to 9 hours of onset or wake stroke was consistent with a core infarct volume <70mL, a penumbra volume >10mL, and a hypoperfusion volume/core infarct volume >1.2. Benefit from intravenous thrombolytic therapy (3 month mRS 0-1 ratio, thrombolytic vs non-thrombolytic: 36% vs 29%). It was also strongly recommended by 2021 ESO guidelines on intravenous thrombolysis for acute ischemic stroke.~For these reasons the investigators hypothesize that endovacular thrombectomy bridging with intravenous thrombolysis is superior to direct thrombectomy in patients of stroke at 4.5 to 9 hours, guided with perfusion imaging.
The primary hypothesis being tested in this trial is that ischemic stroke patients in large vessel occlusion of anterior circulation at 4.5 - 9 hours post onset of stroke will have improved clinical outcomes when given endovascular thrombectomy with intravenous thrombolysis compared with that of given direct endovascular thrombectomy alone.