Age: 18+
Healthy Volunteers: Not accepted
Inclusion Criteria:
1. Age ≥18 years (no upper age limit)
2. Acute ischemic stroke where patient is ineligible for or has failed\* IV thrombolytic treatment and is ineligible for endovascular treatment under best guideline-based care due to absence of proximal arterial occlusion (e.g. intracranial ICA, MCA-M1 and co-dominant or dominant M2\*\* segments, and vertebrobasilar arteries).\*\*\*
\* IV thrombolytic treatment failure is defined by persistent disabling neurological deficits beyond 60 minutes of completion of thrombolytic infusion in the presence of imaging findings consistent with DMVO.
\*\*Dominant M2 segment is defined is a division supplying >50% of the MCA territory vs co-dominant supplying 50% of the MCA territory vs non-dominant supplying <50% of the MCA territory.
\*\*\*No procedures or tests required by the protocol will delay fastest possible delivery of thrombolytic therapy to potentially eligible subjects.
3. Evidence of a primary (e.g. not secondary to EVT of proximal vessel occlusion) distal medium vascular occlusion defined as occlusion of the non-dominant M2 segment or M3 segment of the MCA, the ACA (A1, A2, or A3 segments), or the PCA (P1, P2 or P3 segments) resulting in significant clinical deficits and expected to be treatable by endovascular thrombectomy. Regardless of vessel anatomic location, all vessel diameters should be within 1.5mm -2.5mm. (refer to the device labeling for recommended vessel diameters for each device model.)\*
4. No significant pre-stroke functional disability (mRS ≤2)
5. Evidence of a disabling stroke defined as follows:
1. Baseline National Institutes of Health Stroke Scale (NIHSS) score >5 at the time of randomization.
2. NIHSS 3-5 with disabling deficit including significant aphasia, neglect, hemianopsia, or hemiparesis/ loss of hand or leg function as established by the treating team in context of the patient's life.
6. The presence of a Target Mismatch defined as:
1. Ischemic Core < 50cc (defined on NCCT/CTP\* or DWI-MRI)
\*Visual or automatedly detected hypodensity on NCCT should be used to exclude or include patients if the investigator believes that their assessment is more reliable than the CTP volume in any particular case.
2. Mismatch Volume (TMax >6sec lesion - Core volume lesion) >10cc
3. Mismatch Ratio >1.4
7. Patient treatable within 12 hours of symptom onset. Symptoms onset is defined as the point in time the patient was last seen well (at baseline). Treatment start is defined as the time of arterial puncture.
8. Informed consent obtained from patient or acceptable patient surrogate
Exclusion Criteria:
1. Any sign of intracranial hemorrhage on baseline CT/MR (SDH/SAH/ICH).
2. Rapidly improving symptoms, particularly if in the judgment of the managing clinician that the improvement is likely to result in the patient having no residual disabling deficits and an NIHSS score of <5 at randomization.
3. Significant ischemic changes in a territory other than the occluded site that in the opinion of the investigator could reduce the benefit of endovascular treatment.
4. Contra indication to imaging with MR or CT with contrast agents.
5. Infarct core >1/3 occluded territory (MCA, ACA, or PCA) qualitatively or >50 mL quantitatively (determined by NCCT, CTP or DWI).
6. Any terminal illness such that patient would not be expected to survive more than 1 year.
7. Recent past history or clinical presentation of ICH, subarachnoid hemorrhage (SAH), arterio-venous (AV) malformation, aneurysm, or cerebral neoplasm other than meningioma.
8. Any imaging findings suggestive of futile recanalization in the judgment of the local investigator.
9. Premorbid disability (mRS ≥3).
10. Inability to initiate endovascular treatment within 12 hours of last seen well.
11. Seizures at stroke onset if it precludes obtaining an accurate baseline NIHSS.
12. Baseline blood glucose of <50 mg/dL (2.78 mmol) or >400 mg/dL (22.20 mmol).
13. Known history of hereditary or acquired hemorrhagic diathesis and/or platelet count <100,000/uL.
14. Known renal failure as defined as serum creatinine levels > 3.0 mg/dL.
15. Presumed septic embolus or suspicion of bacterial endocarditis.
16. Any other condition that, in the opinion of the investigator, precludes an endovascular procedure or poses a significant hazard to the subject if an endovascular procedure was performed.
17. History of drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements.
18. Subjects with occlusions in multiple vascular territories (e.g., bilateral or multi-territorial anterior circulation, or anterior/posterior circulation)
19. Subject participating in a study involving an investigational drug or device that would impact this study
20. Known pregnancy
21. Prisoner or incarceration
22. Known acute symptomatic COVID-19 infection