# Acute Ischemic Stroke Reperfusion Selection

Select reperfusion therapy by rapidly separating hemorrhage from ischemia, identifying treatable large-vessel occlusion, estimating infarct extent, and applying time- and tissue-based criteria without delaying intravenous thrombolysis or thrombectomy when indicated.

**Clinical question:** Which patients with acute ischemic stroke should receive intravenous thrombolysis, mechanical thrombectomy, or both?

Updated: 2026-09-15T22:20:17.778552+00:00

## What matters in practice
- Obtain noncontrast head CT immediately to exclude hemorrhage, then add CTA promptly when large-vessel occlusion is possible; do not await perfusion imaging before early-window thrombectomy decisions. [13]
- For anterior-circulation large-vessel occlusion within 6 hours, mechanical thrombectomy plus best medical management is recommended when there is no extensive established infarction, exemplified by ASPECTS at least 6 or infarct core volume no greater than 70 mL. [2]
- In the 6- to 24-hour window, select patients with large-vessel occlusion using DAWN or DEFUSE-3 eligibility criteria rather than clock time alone. [2]
- Give intravenous thrombolysis to otherwise eligible large-vessel-occlusion patients without delaying thrombectomy; intravenous thrombolysis is part of best medical management in thrombectomy guidelines. [1][2][10]
- Treatment speed remains decisive: initiate endovascular thrombectomy as soon as possible after identifying an eligible occlusion. [4]

## Obtain the imaging that changes the reperfusion pathway

Run imaging and transfer decisions in parallel with neurologic assessment and time-last-known-well determination.

Use noncontrast head CT first to exclude intracranial hemorrhage and assess early ischemic change. For potential thrombectomy candidates, add CTA of the head and neck immediately to identify proximal large-vessel occlusion (LVO); in the 0- to 6-hour window, noncontrast CT plus CTA is the core imaging strategy. [13]

Calculate Alberta Stroke Program Early CT Score (ASPECTS) on noncontrast CT for anterior-circulation stroke. In the early window, an ASPECTS of at least 6 is an example of absence of extensive infarct core supporting thrombectomy selection; low ASPECTS should trigger stroke-neurology and neurointerventional discussion rather than automatic procedural exclusion based only on symptom severity. [2]

Do not use an upper NIHSS threshold to deny thrombectomy when CTA shows LVO. ESO–ESMINT recommends thrombectomy plus best medical management for high-severity LVO stroke and specifies no upper NIHSS limit for treatment decisions. [2]
- Known onset or last known well 0-6 hours: noncontrast CT for hemorrhage and ASPECTS, plus CTA for LVO; routine CT or MR perfusion is not required before early-window thrombectomy selection. [13]
- Last known well 6-24 hours or wake-up presentation with suspected LVO: obtain CT perfusion or MR diffusion/perfusion imaging to determine DAWN or DEFUSE-3-type tissue eligibility. [2][13]
- If perfusion imaging is unavailable in the extended window, MRI may identify clinical-core mismatch; do not substitute a normal noncontrast CT for tissue selection in a late-window LVO presentation. [13]

*Imaging sequence and result-dependent reperfusion action. [2][13]*

| Clinical setting | Minimum imaging | Actionable finding | Next action |
| --- | --- | --- | --- |
| Suspected ischemic stroke, any onset time | Noncontrast head CT | No intracranial hemorrhage; assess early ischemic change/ASPECTS [13] | Proceed immediately to vascular imaging when LVO is possible. [13] |
| 0-6 hours, possible anterior-circulation LVO | Noncontrast CT plus CTA | LVO with ASPECTS at least 6 is an example of a nonextensive core profile. [2][13] | Activate thrombectomy pathway; do not wait for perfusion imaging. [2][13] |
| 6-24 hours, LVO | CTA plus CT perfusion or MR diffusion/perfusion | DAWN or DEFUSE-3 inclusion profile [2][13] | Proceed with thrombectomy plus best medical management. [2] |

## Select anterior-circulation LVO for immediate thrombectomy

Early-window selection prioritizes occlusion confirmation, infarct extent, and workflow speed.

For anterior-circulation LVO presenting within 6 hours, perform mechanical thrombectomy (MT) plus best medical management rather than medical management alone when imaging does not show extensive infarct core. Guideline examples of favorable baseline imaging are ASPECTS at least 6 on noncontrast CT or infarct-core volume no greater than 70 mL. [2]

Treat LVO as a procedural emergency after CTA confirmation. Modern thrombectomy trials demonstrated major functional benefit, with numbers needed to treat of 3 for any improvement in functional outcome and 5 for functional independence in the pivotal-trial evidence base; delays in endovascular treatment worsen outcome, so imaging review, interfacility transfer, and angiography-suite activation should occur concurrently. [1][4]

Age alone should not exclude treatment. Guidance supports thrombectomy in older adults, including those older than 80 years, when otherwise eligible; selection should instead emphasize LVO anatomy, established infarct burden, time from last known well, and applicable trial-derived imaging criteria. [1][2]
- Use CTA to establish the LVO diagnosis before committing to an endovascular pathway. [13]
- Use ASPECTS to identify extensive early infarction; ASPECTS at least 6 is a guideline-supported example of early-window eligibility. [2]
- Do not impose an upper NIHSS cutoff once an otherwise eligible LVO is confirmed. [2]
- Target the shortest possible imaging-to-reperfusion workflow; speed should not be traded for nonrequired advanced imaging in the 0- to 6-hour window. [4][13]

*Early-window features that alter the thrombectomy decision. [2][13]*

| Feature | Interpretation | Management implication |
| --- | --- | --- |
| CTA-confirmed anterior-circulation LVO | Treatable arterial target identified. [13] | Evaluate infarct extent and activate MT workflow. [2] |
| ASPECTS at least 6 | Example of no extensive infarct core in guideline selection. [2] | MT plus best medical management is recommended within 6 hours. [2] |
| Infarct core volume no greater than 70 mL | Alternative example of nonextensive core. [2] | Supports early-window MT selection when LVO is present. [2] |
| High NIHSS | Severity alone has no guideline upper limit for MT selection. [2] | Do not withhold MT solely because the NIHSS is high. [2] |

## Use DAWN or DEFUSE-3 criteria for late-window LVO

In late or uncertain-onset stroke, demonstrate salvageable tissue rather than relying on elapsed time alone.

For LVO from 6 to 24 hours after last known well, thrombectomy is recommended when the patient fulfills DAWN or DEFUSE-3 inclusion criteria. This applies to high-severity LVO stroke and extends to patients older than 80 years when the applicable imaging-selection criteria are met. [1][2]

Use CT perfusion or MR diffusion/perfusion to estimate established core and hypoperfused but potentially salvageable tissue. Perfusion-based paradigms move selection from clock time toward tissue status, but very early perfusion acquisition can overestimate ischemic core because infarct evolution and reperfusion may occur after imaging. [14]

Interpret automated or protocol-derived estimates in the clinical and anatomic context. A mismatch profile supports reperfusion only when an occlusion target is present and the patient meets a validated trial-selection framework; perfusion imaging should refine late-window selection, not replace CTA confirmation of LVO. [2][13][14]
- Wake-up stroke: use last known well for initial timing, then pursue advanced tissue imaging if LVO is found and the patient is outside the early window. [2][13]
- CT perfusion: use to assess core-penumbra mismatch in late-window candidates. [13][14]
- MR imaging: diffusion-weighted imaging and perfusion imaging can support tissue-based selection; MRI can also guide assessment of clinical-core mismatch when perfusion imaging is unavailable. [13][14]
- Proceed with MT only when late-window criteria align with DAWN or DEFUSE-3 selection; avoid extrapolating these criteria to every distal or medium-vessel occlusion. [2][6]

### Why core estimates require caution

Perfusion core is not synonymous with irreversible infarction in every patient. In particular, validated cerebral blood flow thresholds may overestimate core when imaging is obtained very early, so an apparently large perfusion-defined core should be reconciled with noncontrast CT, diffusion imaging when available, collateral context, and the time-dependent clinical scenario. [14]

*Late-window tissue-imaging interpretation for LVO thrombectomy selection. [2][13][14]*

| Imaging result | Interpretation | Decision |
| --- | --- | --- |
| CTA shows LVO; CT or MR perfusion meets DAWN or DEFUSE-3 inclusion criteria | Validated late-window target profile. [2][13] | Perform MT plus best medical management. [2] |
| CTA shows LVO; no validated DAWN or DEFUSE-3 profile | Late-window benefit is not established by the cited guideline recommendation. [2] | Individualize through stroke and neurointerventional assessment rather than applying routine late-window MT. [2] |
| Perfusion imaging obtained very early suggests a large core | Core threshold may overestimate irreversible injury. [14] | Reconcile with CT/MRI findings and avoid using perfusion output in isolation. [14] |

## Give eligible intravenous thrombolysis without delaying thrombectomy

Intravenous treatment and endovascular treatment are parallel—not sequential—reperfusion decisions.

For an eligible patient with acute ischemic stroke and LVO who is proceeding to MT, administer intravenous thrombolysis as part of best medical management whenever indicated; do not defer the thrombectomy pathway to observe whether systemic thrombolysis recanalizes the vessel. [1][2][10]

The reason to preserve bridging therapy is that some patients achieve successful reperfusion before the endovascular procedure, potentially averting MT, whereas many proximal LVOs do not achieve complete recanalization with intravenous thrombolysis alone. Procedural activation and transfer must therefore continue during thrombolytic administration. [8][10]

Maintain blood pressure below 185/110 mm Hg before intravenous thrombolysis. During reperfusion therapy, avoid blood pressure above 180/105 mm Hg through early, modest blood-pressure control. [19][20]
- Do not use anticipated MT as a reason to withhold otherwise indicated intravenous thrombolysis. [1][2][10]
- Do not allow thrombolytic administration to delay groin puncture or transfer to an endovascular-capable center. [4][21]
- Use the separate intravenous-thrombolysis eligibility assessment in parallel with CTA-based thrombectomy selection; head CT is the only imaging required before initiating IV thrombolysis. [13]
- Reassess blood pressure before thrombolysis and maintain reperfusion-treatment blood-pressure limits. [19][20]

*Parallel workflow for combined reperfusion therapy. [1][2][10][13][19][20]*

| Decision point | Action | Do not do |
| --- | --- | --- |
| Noncontrast CT excludes hemorrhage and patient is IV-thrombolysis eligible | Start intravenous thrombolysis while CTA and MT activation proceed. [1][2][13] | Do not wait for advanced perfusion imaging before starting IV thrombolysis. [13] |
| CTA confirms LVO and MT criteria are met | Proceed directly to thrombectomy pathway. [2] | Do not wait to determine whether IV thrombolysis achieves recanalization. [10] |
| Blood pressure before IV thrombolysis | Maintain below 185/110 mm Hg. [19] | Do not administer IV thrombolysis above this threshold without BP control. [19] |
| During reperfusion therapy | Avoid BP above 180/105 mm Hg. [20] | Do not pursue intensive BP lowering solely because reperfusion has occurred; optimal post-EVT intensity remains an active question. [5] |

## Avoid automatic extrapolation beyond proven LVO pathways

An occlusion on vascular imaging does not confer identical evidence across vessel territories or infarct profiles.

The strongest recommendation applies to LVO-related anterior-circulation stroke within 6 hours without extensive infarct core, and to 6- to 24-hour LVO meeting DAWN or DEFUSE-3 criteria. A patient outside these profiles should undergo individualized multidisciplinary assessment rather than being labeled ineligible because of a single factor such as age or NIHSS. [1][2]

Medium- or distal-vessel occlusion should not be managed as though it has the same established evidence base as proximal LVO. Recent randomized trials of endovascular treatment for medium-vessel occlusion have produced varying results, making vessel-level anatomy and local neurointerventional expertise especially important to procedural decisions. [6]

When an LVO is identified at a nonthrombectomy hospital, arrange rapid endovascular-capable transfer while continuing indicated medical reperfusion therapy. The expected benefit of MT is time-sensitive, and treatment delay should be treated as a systems failure risk rather than a reason to defer referral. [4][7]
- Escalate immediately to stroke and neurointerventional teams for CTA-confirmed LVO, including older adults and patients with severe deficits. [1][2]
- Use protocolized DAWN or DEFUSE-3 screening for 6- to 24-hour candidates rather than subjective visual assessment alone. [2][13]
- Treat medium-vessel occlusion decisions as individualized because trial results are variable. [6]
- Prioritize transfer and angiography-suite readiness after eligibility is established; every avoidable workflow interval threatens treatment benefit. [4][7]

*When to use established selection pathways versus individualized decision-making. [2][6][13]*

| Scenario | Evidence-based pathway | Practical next step |
| --- | --- | --- |
| Anterior-circulation LVO, 0-6 hours, nonextensive core | MT plus best medical management is strongly recommended. [2] | Proceed without requiring perfusion imaging. [13] |
| LVO, 6-24 hours, DAWN or DEFUSE-3 eligible | MT plus best medical management is recommended. [2] | Proceed using protocol-based tissue selection. [2][13] |
| Medium- or distal-vessel occlusion | Randomized-trial results vary. [6] | Individualize with neurointerventional consultation and anatomy-specific assessment. [6] |

## References
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2. European Stroke Organisation (ESO) - European Society for Minimally Invasive Neurological Therapy (ESMINT) Guidelines on Mechanical Thrombectomy in Acute Ischemic Stroke | Journal of NeuroInterventional Surgery — jnis.bmj.com — https://jnis.bmj.com/content/15/8/e8
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.