Immediate Management of Large Vessel Occlusion Stroke After Non-Contrast CT
In patients with suspected large vessel occlusion (LVO) stroke presenting within 6 hours and no hemorrhage on non-contrast CT, both CT angiography (CTA) and IV thrombolysis should be performed immediately and simultaneously—do not delay either intervention. 1
The Optimal Workflow: Parallel Processing, Not Sequential
The Canadian Stroke Best Practice guidelines explicitly state that patients potentially eligible for endovascular thrombectomy (EVT) within 6 hours should undergo immediate brain imaging with both non-contrast CT AND CT angiography without delay, performed from arch-to-vertex to identify large vessel occlusions. 1 This is Level A evidence and represents the highest standard of care.
Key Principle: Do Not Choose Between Them
The critical error to avoid is treating this as an "either/or" decision. The evidence strongly supports that:
- IV alteplase should be initiated immediately if the patient meets eligibility criteria (within 4.5 hours, no contraindications), even when LVO is suspected and mechanical thrombectomy is being considered. 2, 3
- CTA should be obtained without delay to identify the LVO and plan for EVT. 1
- Never wait to assess clinical response to IV alteplase before proceeding with catheter angiography for mechanical thrombectomy, as any delay worsens outcomes. 2, 3
The Evidence-Based Algorithm
For Patients Presenting Within 6 Hours:
Complete non-contrast CT to exclude hemorrhage 1
Immediately proceed to CTA (arch-to-vertex) while simultaneously:
Administer IV alteplase (0.9 mg/kg, max 90 mg) as soon as eligibility is confirmed, ideally within 30 minutes of arrival (door-to-needle time) 2, 3
Review CTA results to confirm LVO 1
Proceed directly to mechanical thrombectomy if LVO is confirmed, without waiting to see if alteplase works 2, 3
Why Both Interventions Are Essential:
IV alteplase provides early recanalization in 41% of LVO patients, significantly improving outcomes even when mechanical thrombectomy is planned. 4 In the ESCAPE trial, early recanalization with alteplase was associated with nearly double the rate of good functional outcomes (adjusted risk ratio 1.9). 4
CTA is mandatory because it identifies the exact location of the occlusion, allows assessment of collateral circulation, and enables procedural planning for EVT. 1 The multiphase CTA protocol provides information about vessel tortuosity and collateral status that directly impacts treatment decisions. 1
Time-Specific Considerations
Within 0-4.5 Hours:
- IV alteplase is strongly recommended (Level A evidence) 2, 3
- CTA should be obtained simultaneously to identify LVO 1
- Target door-to-needle time <60 minutes (ideally 30 minutes) 2, 3
Within 4.5-6 Hours:
- CTA is essential to identify LVO candidates for EVT 1
- IV alteplase may still be considered in select patients based on advanced imaging 5
- Mechanical thrombectomy remains highly effective 2, 3
Beyond 6 Hours (6-24 Hours):
- Advanced imaging (CT perfusion or MRI-DWI) is required to assess ischemic core and penumbra 1, 2, 3
- Patients with small core and large penumbra or severe clinical deficit remain EVT candidates 2, 3, 5
Critical Pitfalls to Avoid
Do not delay CTA to give alteplase first. The imaging can be obtained while preparing the medication. 1
Do not delay alteplase to wait for CTA results. If the patient is within the thrombolysis window and has no contraindications, start alteplase immediately. 2, 3
Do not observe the patient after alteplase to assess clinical response before proceeding to angiography—this delay significantly worsens outcomes. 2, 3
Do not skip CTA in suspected LVO cases. Even if alteplase is given, you need vascular imaging to determine EVT eligibility. 1
Special Circumstances
Primary Stroke Centers Without CTA Capability:
These centers should complete non-contrast CT, administer IV alteplase if appropriate, and then rapidly transfer the patient to a comprehensive stroke center for CTA and potential EVT. 1 Do not delay transfer waiting to see if alteplase works.
Patients on Anticoagulation:
- Warfarin with INR ≤1.7: IV alteplase may be reasonable 2
- Direct oral anticoagulants (DOACs): Should not routinely receive alteplase, but EVT should still be considered 2
The Bottom Line
The modern approach to LVO stroke is aggressive parallel processing, not sequential decision-making. Both IV thrombolysis and vascular imaging with CTA should occur simultaneously and urgently. 1, 2, 3 This "bridging therapy" approach—IV alteplase followed immediately by mechanical thrombectomy without waiting for clinical response—represents the current standard of care and maximizes the chance of good functional outcomes while minimizing mortality. 2, 3, 4