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Ischaemic Stroke

National Clinical Guideline for Stroke 2023 Edition. NICE Guideline [NG128] Stroke and transient ischaemic attack in over 16s: diagnosis and initial management. Last updated: Apr 2022

Guidelines

In order of priority:
  1. Refer to hyperacute stroke service
  2. Perform history and examination + exclude hypoglycaemia + document NIHSS score
  3. Non-contrast head CT to exclude intracerebral haemorrhage
  4. Once intracerebral haemorrhage is excluded → determine eligibility for thrombolysis and/or thrombectomy
    • If patient is eligible for thrombolysis → perform thrombolysis (and delay aspirin)
    • If patient is NOT eligible for thrombolysis → give aspirin 300mg immediately

If eligible for both thrombolysis and thrombectomy → thrombolysis should be given without delay and activate thrombectomy protocol at the same time. 

Admit all suspected stroke patients directly to hyperacute stroke service

1st line and most important investigation: non-contrast head CT within 1 hour to exclude intracerebral haemorrhage

Further imaging:
  • Diagnostic uncertainty → MRI brain with stroke-specific sequences
 
  • Potentially eligible for thrombolysis and/or thrombectomy
    • CT / MR perfusion (alternative: MRI measuring DWI-FLAIRDiffusion-weighted imaging (DWI)–fluid-attenuated inversion recovery (FLAIR) mismatch)
    • CT angiogram from aortic arch to skull vertex 

If the patient is likely eligible for thrombectomy (e.g. high NIHSS and low modified Rankin score), it is common to order a CT stroke protocol (sequence of scans including non-contrast CT → CT perfusion → CT angiography), which excludes intracerebral haemorrhage and gives the relevant information needed to assess eligibility for thrombectomy.

Admit all suspected stroke patients directly to hyperacute stroke service

The following management options only apply once intracerebral haemorrhage has been excluded.

If CT excludes haemorrhage, and the clinical picture is consistent with acute stroke → you treat as an ischaemic stroke.

This is because, head CT is often normal in the first few hours therefore it is not possible to definitively diagnose or rule out ischaemic stroke.

Aspirin 300mg should be offered ASAP once
  • Intracerebral haemorrhage has been excluded AND
  • Patient is not undergoing thrombolysis

If the patient is dysphagic → enteral / rectal tube

If the decision is made to treat the patient with thrombolysis, aspirin 300mg should only be given 24 hours after thrombolysis (and once repeat imaging excludes haemorrhage). 

Do NOT give aspirin 300mg before thrombolysis.

  • Onset of symptoms <4.5 hours 
  • Last known to be well >4.5 hours earlier if
    • Thrombolysis can be started between 4.5-9 hours or known onset OR within 9 hours of the midpoint of sleep for wake-up stroke, AND
    • Neuroimaging (CT / MR perfusion, or MRI DWI-FLAIR mismatch) shows potential to salvage brain tissue

It is sufficient to just learn that <4.5 hours from onset of symptoms is the eligibility criterion for thrombolysis.

It is very unlikely for any medical school exams or the UKMLA to test a student's knowledge on the 2nd eligibility criterion listed above.

Ensure BP <185/110 mmHg before initiating thrombolysis. 

Agent of choice:  IV alteplase / tenecteplase 

Contraindications outlined by the National Clinical Guideline for Stroke:
  • BP >185/110 mmHg (BP should be lowered prior to thrombolysis)
  • Intracranial haemorrhage (should be excluded with head CT)
  • Known ↑ risk of bleeding
    • Recent major surgery
    • Significant head trauma
    • Known bleeding disorders
    • Patients taking anticoagulant therapy beyond safe therapeutic parameters

It is important to rule out contraindications for thrombolysis while taking a history from a patient with suspected stroke.

Offer thrombectomy in proximal anterior circulation occlusion (confirmed on CTA / MRA) if:
  • <6 hours of symptom onset, OR
  • Last known to be well 6-24 hours (including wake-up strokes) + there is potential to salvage brain tissue

Consider thrombectomy in proximal posterior circulation occlusion ​Basilar / posterior cerebral artery(confirmed on CTA / MRA) if:
  • Last known to be well up to 24 hours (including wake-up strokes), AND
  • There is potential to salvage brain tissue

NICE recommends that thrombectomy is favoured in:
  • Pre-stroke modified Rankin scale <3 (i.e. good pre-stroke functional status)
  • NIHSS >5 (i.e. stroke causing disabling neurological deficits)

Decisions regarding thrombectomy are complicated and are made by neurologists. The general indications for thrombectomy can be categorised into 2 main domains:

  • Clinical factors
    • Disabling / severe neurological deficits (high NIHSS)
    • Good pre-stroke functional status (low modified Rankin scale)
  • Imaging factors
    • Proximal occlusion (i.e. large vessel occlusion) (indicated by angiography)
    • If there is potential to salvage brain tissue (indicated by CT / MR perfusion)

NICE recommends considering decompressive hemicraniectomy within 48 hours if ALL of the following:
  • Clinical features that suggest MCA infarct + NIHSS score >15
  • ↓ Level of consciousness + ≥1 on NIHSS item 1a
  • MCA territory infarct >50% on CT

Rationale: in malignant MCA infarction, extensive cerebral oedema can develop rapidly. Decompressive hemicraniectomy prophylactically prevents cerebral oedema from raising ICP and reduces risk of ICP. 

Offer:
  • High-intensity statin (e.g. atorvastatin 80mg) 
  • Antithrombotic treatment (antiplatelet or anticoagulation)

Choice of antiplatelet vs anticoagulation as long-term antithrombotic treatment depends on the cause of stroke

  • Aspirin 300mg OD continued for 2 weeks after stroke onset
 
  • After 2 weeks → clopidogrel 75mg OD lifelong
    • Alternative: aspirin 75mg OD

If the patient is treated with thrombolysis, antiplatelet therapy should be delayed until 24 hours after AND once repeat imaging excludes haemorrhage.

  • Offer aspirin 300mg OD initially, until anticoagulation is started
 
  • Start anticoagulation 5-14 days after stroke onset (if the stroke is mild, it's possible to start anticoagulation less than 5 days after stroke onset)
    • 1st line for most patients: DOAC (e.g. apixaban)
    • 1st line in valvular AF: warfarin

Note the timing to start anticoagulation in TIA is different from that in ischaemic stroke:

  • In ischaemic stroke with AF, anticoagulation is only started after 5-14 days, with aspirin 300mg being given during those 5-14 days
  • In TIA with AF, anticoagulation can be started immediately, once intracerebral haemorrhage has been excluded


This difference in timing reflects the balance of benefits and bleeding risk in the presence of established infarction (stroke) vs TIA. Anticoagulants carry a much higher risk of intracerebral haemorrhage than antiplatelets.

In ischemic stroke with AF, there is a significant risk of hemorrhagic transformation in the infarcted brain tissue if anticoagulation is started immediately. Therefore, anticoagulation is typically delayed for about 5-14 days, while aspirin 300 mg is given in this period to prevent early recurrent ischemia.


In TIA with AF, there is no established infarcted tissue and thus essentially no risk of hemorrhagic transformation. Once intracerebral haemorrhage is excluded by imaging, anticoagulation can be started immediately to provide early secondary stroke prevention.


But ultimately, for both ischaemic stroke and TIA patients with AF, long-term anticoagulation (not antiplatelet) is required for effective stroke prevention.

References

National Clinical Guideline for Stroke 2023
NICE Guideline Stroke and Transient ischaemic attack in over 16s
Author: Adams Lau
Last edited: 08/10/25