On DSMB advice, trial recruitment has been halted for efficacy. F/U continues.

The purpose of the study is to understand whether a new treatment of stroke - endovascular clot removal - can be added to the current standard of care to improve patient outcomes.

All patients will receive the best standard stroke treatment. This includes treating patients with the clot dissolving drug tPA (tissue plasminogen activator). However, t-PA does not work in some patients and others are not eligible to receive t-PA because they present too late for treatment (they woke up with their stroke symptoms or their stroke was not witnessed).

During endovascular revascularization the blockage in the artery is removed with the use of devices called stentreivers and or by giving clot dissolving drug at the site of the blockage in the artery to restore blood flow. Stentrievers are devices that have been designed by different companies to remove blood clots from arteries.

Up to a maximum of 500 people at 20-25 hospitals across Canada and other countries will participate in this study.

ESCAPE is a phase 3, randomized, open-label with blinded outcome evaluation, controlled, parallel group design.

The primary objectives of this study are to show that rapid endovascular revascularization amongst radiologically selected (small core/proximal occlusion) patients with ischemic stroke results in improved outcome compared to patients treated in clinical routine.

Eligible patients will be enrolled within 12 hours of last seen normal with a baseline NIHSS > 5 at the time of randomization. There must be a 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.

All patients will receive the best standard of medical care according to modern acute stroke care guidelines. Control arm subjects will receive best medical care. In the intervention/experimental arm, subjects will be treated with endovascular thrombectomy or thrombolysis using currently available technology for use in the ESCAPE site for thrombectomy/thrombolysis.

This study consists of one 90-day study period for each subject. Subjects will be hospitalized for care after their acute stroke according to the current standard of care. Subjects are required to return to clinic on Days 30 & 90 for end-of-study procedures.

Inclusion 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.

Exclusion Criteria

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.