Eligibility CriteriaInclusion Criteria A. Clinical (Heterogeneous sampling frame)
1. Acute ischemic stroke
2. Age 18 or greater
3. Onset (last-seen-well) time to randomization time < 12 hours.
4. Disabling stroke defined as a baseline NIHSS > 5 at the time of randomization.
5. Pre-stroke (24 hours prior to stroke onset) independent functional status in activities of daily living with modified Barthel Index > 90. Patient must be living in their own home, apartment or seniors lodge where no nursing care is required.
B. Imaging (Homogeneous target population)
6. Confirmed symptomatic intracranial occlusion, based on single phase, multiphase or dynamic CTA, at one or more of the following locations: Carotid T/L, M1 MCA, or M1-MCA equivalent (2 or more M2-MCAs). Anterior temporal artery is not considered an M2.
7. Non-contrast CT and CTA for trial eligibility performed or repeated at ESCAPE stroke center with endovascular suite on-site.
8. Endovascular treatment intended to be initiated (groin puncture) within 60 minutes of baseline non-contrast CT with target baseline non-contrast CT to first recanalization of 90 minutes.
9. Signed informed consent or appropriate signed deferral of consent where approved.
1. Baseline non-contrast CT reveals a moderate/large core defined as extensive early ischemic changes of ASPECTS 0-5 in the territory of symptomatic intracranial occlusion.
2. Other confirmation of a moderate to large core defined one of three ways:
1. On a single phase, multiphase or dynamic CTA: no or minimal collaterals in a region greater than 50% of the MCA territory when compared to pial filling on the contralateral side (multiphase/dynamic CTA preferred) OR
2. On CT perfusion (>8 cm coverage): a low CBV and very low CBF ASPECTS <6 AND in the symptomatic MCA territory OR
3. On CT perfusion(<8 cm coverage): a region of low CBV and very low CBF >1/3 of the CTP imaged symptomatic MCA territory.
3. Groin puncture is not possible within 60 minutes of the first slice of non-contrast CT acquisition (please note that if CTP is performed it should be done after CTA).
4. No femoral pulses or very difficult endovascular access that will result in a non-contrast CT-to-recanalization time that is longer than 90 minutes, or will result in an inability to deliver endovascular therapy.
5. Pregnancy; if a woman is of child-bearing potential a urine or serum beta HCG test is positive.
6. Severe contrast allergy or absolute contraindication to iodinated contrast.
7. Suspected intracranial dissection as a cause of stroke.
8. Clinical history, past imaging or clinical judgment suggests that the intracranial occlusion is chronic.
9. Patient has a severe or fatal comorbid illness that will prevent improvement or follow-up or that will render the procedure unlikely to benefit the patient.