What type of strokes are suitable for thrombectomy?

Strokes Suitable for Mechanical Thrombectomy

Mechanical thrombectomy is strongly recommended for patients with acute ischemic stroke due to large vessel occlusion in the anterior circulation, regardless of NIHSS score (though patients with NIHSS ≥6 have stronger evidence), with treatment initiated within 24 hours of symptom onset if they meet appropriate clinical-imaging criteria. 1

Primary Eligibility Criteria

Time Windows

• 0-6 hours from symptom onset:

  • Patients with large vessel occlusion (LVO) in the anterior circulation 2, 1
  • No strict NIHSS threshold, though evidence is stronger for NIHSS ≥6 1

• 6-16 hours from symptom onset:

  • Must meet DAWN or DEFUSE 3 clinical-imaging mismatch criteria 1, 3
  • Requires advanced imaging (CT perfusion or MRI) 1

• 16-24 hours from symptom onset:

  • Must meet DAWN clinical-imaging mismatch criteria 1, 3
  • Requires advanced imaging (CT perfusion or MRI) 1

Vessel Occlusion Locations

• Strong recommendation (Level I, Evidence A):

  • Internal carotid artery (ICA) occlusion 2, 1
  • Proximal middle cerebral artery (M1 segment) occlusion 2, 1

• Reasonable in selected patients (Level IIb):

  • M2/M3 MCA occlusions 1
  • Anterior cerebral, vertebral, basilar, or posterior cerebral artery occlusions 1

Patient Selection Considerations

Core Clinical Criteria

• Age ≥18 years 1
• Pre-stroke modified Rankin Scale (mRS) score of 0-1 (independent functioning) 1
• Alberta Stroke Program Early CT Score (ASPECTS) ≥6 (limited early ischemic changes) 2, 1

Special Populations

• Mild deficits (NIHSS <6):

  • May be reasonable for carefully selected patients with ICA or M1 occlusion 2, 1
  • Higher risk of symptomatic intracerebral hemorrhage compared to medical management 4
  • M1 occlusions may show greater benefit than other locations 4, 5

• Elderly patients (≥80 years):

  • Should not be excluded based on age alone 6
  • May have significant benefit from thrombectomy despite age 6

• Patients with chronic kidney disease:

  • Limited evidence, but may have higher risk of 90-day mortality 2
  • Benefits likely outweigh risks given poor outcomes with medical management alone 2

Technical Considerations

• The technical goal should be achieving modified TICI grade 2b/3 reperfusion (substantial or complete restoration of blood flow) 2, 1
• Stent retrievers are indicated in preference to other mechanical devices 2
• Proximal balloon guide catheter or large-bore distal-access catheter may be beneficial 2
• Intravenous thrombolysis should not be withheld if indicated, and mechanical thrombectomy should not be delayed to assess response to IV thrombolysis 2, 1

Contraindications and Cautions

• Treatment beyond 24 hours from symptom onset is not currently recommended 1
• ASPECTS <6 (extensive early ischemic changes) may have less benefit, but thrombectomy may still be reasonable in selected cases 2, 1
• Pre-existing significant disability (mRS >1) generally has less benefit, but thrombectomy may still be reasonable in selected cases 2, 1

Evolution of Guidelines

It's important to note that the recommendations for mechanical thrombectomy have evolved significantly. The 2012 American College of Chest Physicians guidelines suggested against mechanical thrombectomy 2, but multiple subsequent randomized trials have demonstrated clear benefit, leading to strong recommendations in current guidelines 2, 1, 3. The number needed to treat to reduce disability by at least one level on the modified Rankin Scale is only 2.6 6, making mechanical thrombectomy one of the most effective interventions in stroke care.

The paradigm has shifted from a strict time window to a "tissue window" concept, where patient selection is based on salvageable brain tissue identified through clinical-imaging mismatch rather than solely on time from symptom onset 3.