Aspirin Monotherapy in Acute Ischemic Stroke
Yes, aspirin alone can and should be started in acute ischemic stroke, but only after brain imaging has excluded hemorrhage, and it should be initiated within 24-48 hours of symptom onset at a dose of 160-325 mg daily. 1, 2
Critical First Step: Rule Out Hemorrhage
- Brain imaging (CT scan) is mandatory before administering any aspirin to exclude intracranial hemorrhage 3, 2
- Aspirin administration in hemorrhagic stroke worsens bleeding and increases mortality 3
- If immediate imaging is unavailable, it is safer to delay aspirin until hemorrhage is definitively ruled out 3
Aspirin Dosing and Timing in Acute Ischemic Stroke
Recommended dose: 160-325 mg daily, started within 24-48 hours of stroke onset 1, 2
- This carries Class I, Level of Evidence A recommendation from the American Heart Association/American Stroke Association 2
- The primary benefit is reduction of early recurrent stroke rather than limiting neurological damage from the initial stroke 2
- Treatment prevents approximately 10 deaths and early recurrent strokes per 1,000 patients treated 4, 5
Critical Contraindications and Timing Restrictions
Do NOT give aspirin in these situations:
- Within 24 hours of thrombolytic (tPA) therapy - this significantly increases bleeding risk 2
- As a substitute for IV tPA in eligible patients - aspirin is not equivalent to thrombolysis 2
- In patients with aspirin allergy or active gastrointestinal bleeding 2
- Before brain imaging excludes hemorrhage 3, 2
Long-Term Antiplatelet Strategy After Acute Phase
For secondary stroke prevention beyond the acute period, aspirin monotherapy remains effective but other options exist:
- Aspirin 75-325 mg daily is proven effective for long-term secondary prevention 1
- Lower doses (75-100 mg daily) have similar efficacy to higher doses with fewer gastrointestinal side effects 1, 6
- For intracranial large artery atherosclerosis (50-99% stenosis), aspirin 325 mg daily is preferred over warfarin 1
When Dual Antiplatelet Therapy May Be Considered
While the question asks about aspirin alone, it's important to note situations where dual therapy is superior:
- For recent stroke/TIA (within 30 days) with severe intracranial stenosis (70-99%), adding clopidogrel 75 mg to aspirin for up to 90 days is reasonable 1
- However, long-term dual antiplatelet therapy (beyond 90 days) increases bleeding risk without clear benefit in most stroke patients 1
- The MATCH trial showed no benefit of clopidogrel plus aspirin versus clopidogrel alone for long-term secondary prevention, with increased major bleeding 1
Common Pitfalls to Avoid
- Never use aspirin as a substitute for thrombolysis in eligible patients - this is a critical error 2
- Never give aspirin within 24 hours of tPA administration due to hemorrhagic risk 2
- Never start aspirin without brain imaging first - this could be fatal in hemorrhagic stroke 3
- Don't assume higher doses are better - doses above 325 mg increase bleeding without improving efficacy 1, 6