What are the recommendations and considerations for performing a thrombectomy in a patient with acute ischemic stroke?

Mechanical Thrombectomy for Acute Ischemic Stroke

Mechanical thrombectomy with stent retrievers is strongly recommended for eligible patients with acute ischemic stroke due to large vessel occlusion in the anterior circulation, as it dramatically improves functional outcomes with a number needed to treat of less than 3. 1, 2

Primary Eligibility Criteria (0-6 Hours)

Perform mechanical thrombectomy if ALL of the following criteria are met: 1, 3

• Age ≥18 years 1, 3
• Pre-stroke modified Rankin Scale (mRS) score 0-1 (functionally independent) 1, 3
• NIHSS score ≥6 (moderate to severe deficit) 1, 3
• ASPECTS ≥6 (limited early ischemic changes) 1, 3
• Causative occlusion of internal carotid artery (ICA) or middle cerebral artery M1 segment 1, 3
• Treatment initiation (groin puncture) within 6 hours of symptom onset or last known well 1, 3

Extended Time Window (6-24 Hours)

Mechanical thrombectomy is recommended for carefully selected patients presenting 6-24 hours after last known well who demonstrate salvageable brain tissue on advanced imaging. 1, 3

Requirements for Extended Window Treatment:

• Large vessel occlusion in anterior circulation (ICA or MCA-M1) 1, 3
• Advanced imaging with CT perfusion or MRI diffusion-weighted imaging to demonstrate core-perfusion mismatch 1, 3
• Sizable mismatch between ischemic core and either clinical deficits or area of hypoperfusion 1, 3
• Meet DAWN or DEFUSE-3 eligibility criteria for patient selection 3

The evidence supporting extended window thrombectomy is robust, with high-certainty data showing benefit up to 24 hours in appropriately selected patients. 2, 4

Critical Pre-Procedural Steps

Imaging Requirements:

• Non-invasive angiography (CTA) is mandatory for all patients with clinically suspected large vessel occlusion 1, 3
• Do NOT delay thrombectomy to evaluate response to IV thrombolysis - proceed directly to angiography without waiting 1, 3
• Advanced imaging (CTP or DWI-MRI) is required for patients presenting 6-24 hours after last known well 1, 3

Thrombolysis Considerations:

• Administer IV alteplase to all eligible patients even if mechanical thrombectomy is planned - do not withhold thrombolysis 1, 3
• Initiate thrombectomy preparation immediately without observing for clinical response to IV alteplase 1, 3

This represents a critical shift from older 2012 guidelines 1 which suggested against mechanical thrombectomy (Grade 2C). The 2015 AHA/ASA focused update 1 and 2023 World Stroke Organization guidelines 1 now strongly support thrombectomy based on multiple positive randomized trials demonstrating unequivocal benefit. 2, 5

Technical Goals and Device Selection

Procedural Targets:

• The technical goal is modified TICI grade 2b/3 reperfusion (≥50% reperfusion of target territory) 1, 3
• Use stent retrievers as first-line devices - they are superior to older MERCI devices 1, 3
• Consider proximal balloon guide catheter or large-bore distal access catheter rather than cervical guide catheter alone to improve outcomes 1

Salvage Techniques:

• Intra-arterial fibrinolysis may be reasonable as salvage therapy if TICI 2b/3 is not achieved, but only if completed within 6 hours of onset 1
• Stent retrievers are recommended over intra-arterial fibrinolysis as first-line therapy 1

Special Populations and Scenarios

Expanded Indications:

• Thrombectomy can be considered for cervical ICA occlusion or stenosis in addition to intracranial large vessel occlusion 1, 3
• Thrombectomy may be reasonable for M2/M3 MCA segments, anterior cerebral arteries, vertebral arteries, basilar artery, or posterior cerebral arteries within 6 hours in carefully selected patients 3

Patients with Less Favorable Profiles:

Thrombectomy may be reasonable (but with less certainty) for: 3

• Pre-stroke mRS >1 (pre-existing disability)
• ASPECTS <6 (more extensive early ischemic changes)
• NIHSS <6 (milder deficits)

These patients require individualized assessment weighing uncertain benefits against procedural risks. 3

Systems of Care Requirements

Thrombectomy must be performed at experienced stroke centers with immediate access to cerebral angiography and credentialed interventionalists. 1, 3

Infrastructure Mandates:

• Transport patients rapidly to the closest certified primary or comprehensive stroke center capable of providing thrombectomy 1, 3
• Primary stroke centers should develop capability for emergency non-invasive intracranial vascular imaging to facilitate appropriate patient selection and transfer 1
• Regional systems of stroke care should coordinate rapid transport between facilities providing initial care and those capable of endovascular treatment 1

Outcomes and Efficacy

Mechanical thrombectomy increases the chance of good functional outcome (mRS 0-2) by 50% compared to medical therapy alone (RR 1.50,95% CI 1.37-1.63). 2

Additional benefits include: 2

• Reduced mortality (RR 0.85,95% CI 0.75-0.97)
• Improved neurological recovery to NIHSS 0-1 (RR 2.03,95% CI 1.21-3.40)
• Higher recanalization rates (RR 3.11,95% CI 2.18-4.42)
• No increased risk of symptomatic intracranial hemorrhage (RR 1.05,95% CI 0.72-1.52)

The number needed to treat is less than 3 for improved functional outcome, representing unmatched efficacy in stroke medicine. 5

Common Pitfalls and Safety Considerations

Critical Errors to Avoid:

• Never delay thrombectomy to observe response to IV thrombolysis - this wastes precious time without improving outcomes 1, 3
• Do not withhold IV alteplase from eligible patients simply because thrombectomy is planned - both therapies should be administered 1, 3
• Strict adherence to DAWN or DEFUSE-3 criteria is essential for patient selection in the 6-24 hour window 3

Procedural Complications:

Overall risk of complications with sequelae is approximately 15%, including: 6

• Access site problems (vessel/nerve injury, hematoma, infection)
• Device-related complications (vasospasm, arterial perforation, dissection)
• Symptomatic intracranial hemorrhage
• Embolization to new territories

Early detection and appropriate management of complications minimizes their impact. 6

Cost-Effectiveness and Long-Term Outcomes

Thrombectomy is highly cost-effective and demonstrates long-term efficacy for both disability and mortality outcomes beyond the acute phase. 4 The dramatic improvement in functional independence translates to substantial reductions in long-term care costs and improved quality of life. 2, 4