STEP: Medium Vessel Occlusion Strata

Important Links:

  1. In-person consent
  2. Remote Consent
  3. WebDCU: Enrollment and Randomization
  4. Enrollment and Randomization Instructions

Inclusion Criteria:

  1. Suspected diagnosis of acute ischemic stroke
  2. Likely causative intracranial large or medium vessel occlusion
  3. Age 18 years or older
  4. Pre-stroke modified Rankin Scale 0-2
  5. Presentation to enrolling hospital within 24 hours of last known well/stroke onset
  6. Able to initiate arterial puncture within 2 hours from qualifying CTA/MRA or CTP/MRP imaging
    • CT/MR and qualifying CTA/MRA or CTP/MRP should be repeated if more than 120 minutes have elapsed since the imaging and randomization has not been performed
  7. Visualized complete occlusion or perfusion deficit (Tmax greater than 4s) supportive of a cortical branch occlusion in one of the following vessels: non-dominant/co-dominant M2 or M3
    • Non-dominant/co-dominant M2 is defined as serving less than or equal to 50 percent of entire overall MCA territory.
  8. If symptom onset is greater than 6 hours, the core must be less than 50 percent of the territory supplied by the occluded vessel
    • As evident by either hypodensity and loss of grey-white border on NCCT or ADC less than 620mm2/s on diffusion MRI or rCBF less than 30 percent on CTP
  9. NIHSS greater than or equal to 8

Exclusion Criteria:

  1. Proven contraindication to endovascular thrombectomy
  2. Prisoner or incarcerated
  3. Presumed septic embolus; suspicion of bacterial endocarditis
  4. Seizure at stroke onset or between onset and enrollment
  5. Known anaphylactic reaction to contrast material that precludes endovascular reperfusion therapy
  6. Intracranial occlusion suspected to be chronic, based on history and/or imaging
  7. Intracranial dissection, based on history and/or imaging
  8. Cerebral vasculitis, based on history and/or imaging
  9. Known pregnancy
  10. Known pre-existing medical, neurological, or psychiatric disease that would confound the neurological or functional evaluations
  11. Known serious, advanced, or terminal illness or life expectancy less than 6 months in the investigator judgment
  12. Known or high suspicion for underlying intracranial atherosclerotic disease
  13. Known platelet count less than 100,000/uL
  14. CT ASPECT score less than 6 or MRI ASPECT score less than 7
  15. Unfavorable vascular anatomy that limits access to the occluded artery precluding endovascular reperfusion therapy
  16. Acute occlusions in multiple vascular territories
    • E.g., bilateral anterior circulation, or anterior/posterior circulation
  17. Tandem occlusions
  18. Significant mass effect with midline shift
    • Greater than 5mm
  19. Evidence of intraaxial tumor
    • Except small meningioma
  20. Evidence of acute intracranial hemorrhage

How do I decide if the M2 is dominant or non-dominant? If CTP available, a general rule is to look at Tmax >4 seconds (NOT >6 seconds!) perfusion maps – look at RAPID maps that break down perfusion by different Tmax thresholds to find the >4 s map – if >100 cc perfusion defect, M2 is likely dominant, if < 100cc likely non=dominant