EVT Eligibility Pathway — Mechanical Thrombectomy Decision Support
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Frequently asked questions
Who is eligible for EVT (mechanical thrombectomy)?
Per AHA/ASA 2026 guidelines, EVT is indicated for acute ischemic stroke from a large vessel occlusion (LVO) involving the internal carotid artery, M1 or M2 segment of the middle cerebral artery, or basilar artery, in patients with pre-stroke mRS 0–2. Within the first 6 hours, EVT is indicated regardless of ASPECTS score. In the extended 6–24 hour window, EVT requires clinical-imaging mismatch (DAWN criteria) or perfusion mismatch (DEFUSE-3 criteria). A major 2026 update: large core infarct (ASPECTS 3–5) is now a COR 1 indication based on SELECT-2 and ANGEL-ASPECT trials, demonstrating benefit even with large established infarcts. NIHSS ≥6 is a common practical threshold, though lower scores with disabling deficits may also qualify. Patient age alone is not an exclusion criterion.
What is the EVT time window for stroke thrombectomy?
The EVT time window has two phases. The early window (0–6 hours from last known well) permits thrombectomy for any LVO without perfusion imaging requirements; ASPECTS does not preclude eligibility. The extended window (6–24 hours) requires additional imaging: DAWN criteria (clinical-imaging mismatch — infarct core ≤51 mL for age ≥80 or ≤31 mL for NIHSS ≥10 and age <80) or DEFUSE-3 criteria (core <70 mL, mismatch ratio ≥1.8, mismatch volume ≥15 mL). For basilar artery occlusion, EVT can be considered up to 24 hours based on ATTENTION and BAOCHE trials. Wake-up stroke with favorable perfusion imaging also qualifies at experienced centers. Every 30-minute reduction in time-to-reperfusion significantly improves functional outcomes — time is neurons.
What ASPECTS score is required for mechanical thrombectomy?
ASPECTS (Alberta Stroke Program Early CT Score) quantifies early ischemic changes across 10 MCA territory regions on non-contrast CT, scored 0–10 (lower = larger core). For early window EVT (0–6 hours), the 2026 AHA/ASA guidelines set no minimum ASPECTS cutoff; even low-ASPECTS patients may benefit. For the extended window, ASPECTS ≥6 was required in the original DAWN and DEFUSE-3 trials. A landmark update: large core infarct (ASPECTS 3–5) is now COR 1 based on SELECT-2 (NEJM 2023) and ANGEL-ASPECT (NEJM 2023), which showed clinical benefit despite large established infarcts. ASPECTS 0–2 remains a relative contraindication given very high hemorrhage risk. CT perfusion or MRI DWI provides more accurate core volume assessment than ASPECTS alone in borderline cases.
Should IV tPA be given before EVT (bridging therapy)?
IV thrombolysis before EVT — known as bridging therapy — is recommended when the patient is eligible for both treatments. Per AHA/ASA 2026 guidelines, IV alteplase or tenecteplase should not be withheld in tPA-eligible patients who also qualify for EVT. Giving tPA first does not significantly delay thrombectomy and may improve recanalization of distal emboli. Multiple trials (MR CLEAN-NOIV, SKIP, DIRECT-MT) tested direct EVT versus bridging; pooled data favor bridging for most patients. Tenecteplase is increasingly preferred over alteplase for its single-bolus administration and superior vessel recanalization. Door-to-needle target is <60 minutes and must not delay door-to-puncture target of <90 minutes. In patients with clear tPA contraindications (recent surgery, therapeutic anticoagulation), direct EVT is performed without bridging.
What is the procedure for mechanical thrombectomy (EVT)?
Mechanical thrombectomy is a minimally invasive endovascular procedure performed by a neurointerventionalist under fluoroscopic guidance. A microcatheter is advanced through the femoral or radial artery into the occluded intracranial vessel. A stent retriever or aspiration catheter captures and extracts the clot, restoring cerebral blood flow. The procedure takes 30–90 minutes from groin puncture to reperfusion. Success is measured by modified TICI score: TICI 2b–3 (successful reperfusion) is achieved in approximately 80–85% of modern cases. Conscious sedation is generally preferred over general anesthesia to avoid delays and allow neurological monitoring. Post-procedure care in a stroke or neurological ICU for 24–48 hours monitors for hemorrhagic transformation, manages blood pressure, and assesses neurological recovery with serial NIHSS assessments.