How long should a patient with a history of stroke be on aspirin (acetylsalicylic acid) 325 mg daily?

Duration of Aspirin 325 mg Therapy After Stroke

For patients with non-cardioembolic ischemic stroke, aspirin 325 mg should be continued indefinitely or until an alternative antithrombotic regimen is started. 1

Initial Aspirin Therapy After Stroke

• All acute ischemic stroke patients not already on an antiplatelet agent and not receiving tPA therapy should receive at least 160 mg of aspirin immediately as a one-time loading dose after brain imaging has excluded intracranial hemorrhage and dysphagia screening has been performed and passed 1
• For patients treated with tPA, aspirin should be delayed until after the 24-hour post-thrombolysis scan has excluded intracranial hemorrhage 1
• Aspirin (81 to 325 mg daily) should then be continued indefinitely or until an alternative antithrombotic regimen is started 1

Long-Term Aspirin Therapy

• For non-cardioembolic ischemic stroke or TIA, aspirin 50–325 mg is recommended for long-term secondary prevention 1
• The optimal dose range appears to be 75-162 mg daily for long-term maintenance therapy, which balances efficacy with reduced bleeding risk 1
• For patients with extracranial carotid or vertebral atherosclerosis who have had ischemic stroke or TIA, treatment with aspirin alone (75–325 mg daily) should be continued 1

Special Considerations

Specific Stroke Subtypes

• For patients with stroke related to 50%–99% intracranial stenosis, a higher dose of 325 mg/day aspirin is specifically recommended 1
• For patients with recent minor (NIHSS ≤3) non-cardioembolic ischemic stroke or high-risk TIA (ABCD2 score ≥4), dual antiplatelet therapy (aspirin plus clopidogrel) should be used for 21-90 days, followed by single antiplatelet therapy 1, 2

Alternative Antiplatelet Regimens

• In patients already on aspirin prior to ischemic stroke or TIA, clopidogrel 75 mg daily may be considered as an alternative 1
• For patients who cannot tolerate aspirin, clopidogrel 75 mg daily is recommended as an alternative 1

Dosing Considerations

• Multiple studies have shown that aspirin doses as low as 30 mg daily are effective for stroke prevention 3, 4
• However, during the acute phase after stroke, a higher dose (160-325 mg) is recommended to achieve rapid platelet inhibition 5
• For long-term therapy, there is no significant difference in efficacy between low (30-100 mg), medium (300-325 mg), and high (>900 mg) doses of aspirin, with relative risk reductions of 13%, 9%, and 14% respectively 4
• Lower doses (75-162 mg) are associated with fewer gastrointestinal side effects and bleeding complications 6, 3

Common Pitfalls and Caveats

• Aspirin should not be considered a substitute for other acute interventions for treatment of stroke, including intravenous tPA 1
• Aspirin administration as adjunctive therapy within 24 hours of thrombolytic therapy is not recommended 1
• For patients with cardioembolic stroke (e.g., atrial fibrillation), oral anticoagulation is preferred over antiplatelet therapy 1
• When switching from dual antiplatelet therapy to monotherapy, ensure patients understand the importance of continuing at least one antiplatelet agent indefinitely 1, 2

Monitoring and Safety

• Monitor for signs of bleeding, especially gastrointestinal bleeding, which is dose-related and more common at higher doses 6, 7
• In patients with dysphagia, aspirin may be given by enteral tube (80 mg daily) or by rectal suppository (325 mg daily) 1
• For patients requiring warfarin in addition to aspirin (e.g., for atrial fibrillation), the combination increases bleeding risk and should be monitored closely 1