What is the recommended dose of aspirin (acetylsalicylic acid) for secondary prevention after a stroke?

Aspirin Dosage for Secondary Stroke Prevention

For secondary prevention after a stroke, low-dose aspirin (75-100 mg daily) is recommended as it provides effective protection against recurrent stroke while minimizing bleeding risks. 1

Evidence-Based Dosing Recommendations

The optimal aspirin dose for secondary stroke prevention has been established through multiple guidelines and clinical trials:

• The American Heart Association/American Stroke Association recommends aspirin 75-100 mg daily for secondary stroke prevention 1
• The European Society of Cardiology supports low-dose aspirin (75-100 mg daily) for long-term secondary prevention 1
• Canadian Stroke Best Practice Recommendations suggest maintenance doses of 81-325 mg daily after an initial loading dose 1

Acute vs. Maintenance Dosing

There is an important distinction between initial and maintenance dosing:

• Initial loading dose: 160-325 mg immediately after stroke diagnosis and exclusion of hemorrhage 1, 2
• Maintenance dose: 75-100 mg daily for long-term secondary prevention 1

Rationale for Low-Dose Recommendation

The recommendation for low-dose aspirin is based on:

1. Equivalent efficacy: Studies show that low doses (75-100 mg) are as effective as higher doses for long-term stroke prevention 1, 3

2. Reduced adverse effects: Higher doses increase the risk of gastrointestinal bleeding without providing additional preventive benefit 1, 3

3. Long-term safety: Daily aspirin doses of 75-100 mg provide the optimal balance between antithrombotic efficacy and bleeding risk 1

Special Considerations

Dual Antiplatelet Therapy

• Short-term dual antiplatelet therapy (aspirin plus clopidogrel) may be beneficial for 21-30 days after minor stroke or high-risk TIA 1
• After this period, patients should return to antiplatelet monotherapy with aspirin 75-100 mg daily 1

Alternative Antiplatelet Options

• For patients intolerant to aspirin, clopidogrel 75 mg daily is a reasonable alternative 1
• The PRoFESS trial found no significant difference between clopidogrel and aspirin-dipyridamole for secondary stroke prevention 1

Common Pitfalls to Avoid

1. Using excessive doses: Higher maintenance doses (>100 mg daily) increase bleeding risk without improving efficacy 1, 3

2. Inadequate initial loading: Failing to provide an adequate loading dose (160-325 mg) in the acute setting 1, 2

3. Prolonged dual antiplatelet therapy: Continuing aspirin plus clopidogrel beyond 30 days increases bleeding risk without additional benefit for most patients 1

4. Delayed initiation: Aspirin should be started within 24-48 hours after stroke onset (after excluding hemorrhage) 2

5. Premature discontinuation: Long-term adherence is essential as secondary prevention benefits continue indefinitely 1

In conclusion, while higher doses (160-325 mg) are appropriate for the initial treatment of acute ischemic stroke, the evidence strongly supports transitioning to low-dose aspirin (75-100 mg daily) for long-term secondary prevention to optimize the balance between efficacy and safety.