Large Proximal Vessel Strokes Eligible for Endovascular Treatment
The most clearly established large proximal vessel occlusions eligible for endovascular thrombectomy are internal carotid artery (ICA) and proximal middle cerebral artery (M1 segment) occlusions, with basilar artery occlusions now also having strong evidence for treatment. 1
Anterior Circulation Large Vessel Occlusions
Strongest Evidence (Class I Indication)
Internal Carotid Artery (ICA) occlusion - This represents the most proximal anterior circulation occlusion and has the strongest evidence for EVT benefit within 6 hours of symptom onset 1
Proximal Middle Cerebral Artery (M1 segment) occlusion - Along with ICA occlusions, M1 occlusions are the prototypical large vessel occlusions with Class I evidence for thrombectomy 1, 2
These patients should meet the following criteria for strongest benefit: prestroke modified Rankin Scale (mRS) score 0-1, NIHSS score ≥6, ASPECTS ≥6, age ≥18 years, and treatment initiated within 6 hours of symptom onset 1
Reasonable Evidence (Class IIa-IIb)
M2 segment (secondary division) MCA occlusions - While benefits are less certain than M1 occlusions, EVT may be reasonable for carefully selected patients with M2 occlusions within 6 hours 1
M3 segment (tertiary division) MCA occlusions - These more distal occlusions have uncertain benefit, though EVT may be considered in select cases 1. Recent evidence from the DISTAL trial showed no significant benefit for medium/distal vessel occlusions including M3 segments 3
Anterior Cerebral Artery (ACA) occlusions - A1, A2, or A3 segment occlusions may be considered for EVT on a case-by-case basis, though evidence is limited 1
Posterior Circulation Large Vessel Occlusions
Strongest Evidence (Class I Indication)
- Basilar Artery occlusion - Recent randomized controlled trials (ATTENTION and BAOCHE) have established strong evidence for EVT in basilar artery occlusions within 12 hours of symptom onset 1
Patients should have: NIHSS score ≥6, posterior circulation ASPECTS (PC-ASPECTS) ≥6, age 18-89 years, and confirmed basilar artery occlusion on CT angiography 1
Reasonable Evidence (Class IIa-IIb)
Vertebral Artery occlusion - EVT may be reasonable for vertebral artery occlusions within 6 hours, though evidence is less robust than for basilar occlusions 1
Posterior Cerebral Artery (PCA) occlusions - P1 and P2 segment occlusions may be considered for EVT in carefully selected patients, though benefits are uncertain 1
Extended Time Window Considerations
For patients presenting 6-24 hours from last known well, the following large vessel occlusions remain eligible with advanced imaging selection:
ICA or M1 occlusions with favorable perfusion imaging - Patients with small ischemic core (<70 mL in DEFUSE-3, specific clinical-core mismatch criteria in DAWN) and significant penumbra can benefit from EVT up to 16-24 hours 4, 5
Basilar artery occlusions 12-24 hours from onset - EVT is reasonable for basilar occlusions within 12-24 hours with appropriate patient selection (Class IIa evidence) 1
Large Core Strokes
Recent evidence has expanded eligibility to include patients with larger ischemic cores:
- ICA or M1 occlusions with ASPECTS 3-5 - Patients presenting within 6 hours with ASPECTS scores of 3-5 (representing larger cores) now have evidence supporting EVT, with numbers needed to treat of 4.7 for better functional outcomes 1, 6
Common Pitfalls to Avoid
Do not delay EVT while waiting for response to IV tPA - Patients eligible for both treatments should receive them in parallel, as observing for clinical response is not required and may worsen outcomes 1, 2
Do not exclude patients based solely on time beyond 6 hours - Use advanced imaging (CT perfusion or MRI) to identify salvageable tissue in the 6-24 hour window for anterior circulation strokes 4, 5
Do not automatically exclude M2 occlusions - While evidence is weaker than M1, symptomatic M2 occlusions with significant deficits may benefit from EVT 1
Recognize that more distal occlusions (M3, M4, distal ACA/PCA) lack proven benefit - Recent trial data suggests EVT for medium/distal vessel occlusions does not improve outcomes compared to medical management alone 3