When should aspirin be administered to a patient with an ischemic stroke?

Aspirin Administration in Ischemic Stroke

Oral aspirin (initial dose 325 mg) should be administered within 24 to 48 hours after ischemic stroke onset for most patients. 1

Primary Recommendations

• Aspirin therapy (160-325 mg) should be started within 24-48 hours of stroke onset to reduce stroke mortality and decrease morbidity 1
• The primary benefit of early aspirin administration is reduction of early recurrent stroke rather than limitation of neurological consequences of the initial stroke 1
• Aspirin administration within 48 hours results in approximately 10 fewer deaths and early recurrent strokes per 1,000 patients treated 2, 3
• For patients who cannot swallow safely, aspirin can be administered rectally as a suppository 2

Important Contraindications and Precautions

• Aspirin should NOT be considered a substitute for intravenous recombinant tissue plasminogen activator (rtPA) in eligible patients 1
• Aspirin (or other antiplatelet agents) should NOT be administered as adjunctive therapy within 24 hours of thrombolytic therapy 1
• Aspirin should be avoided in patients with contraindications such as allergy or active gastrointestinal bleeding 1

Evidence Quality and Outcomes

• The recommendation for aspirin administration within 24-48 hours carries a Class I, Level of Evidence A rating in American Heart Association/American Stroke Association guidelines 1
• Early aspirin therapy reduces the risk of death or dependency at 6 months follow-up 3, 4
• The benefit of aspirin appears to be due to prevention of early recurrent ischemic stroke without a major risk of hemorrhagic complications 3, 4

Other Antiplatelet Agents in Acute Stroke

• Clopidogrel alone or in combination with aspirin is not recommended for routine treatment of acute ischemic stroke 1
• The usefulness of clopidogrel for acute ischemic stroke is not well established (Class IIb; Level of Evidence C) 1
• Intravenous antiplatelet agents that inhibit glycoprotein IIb/IIIa receptors are not recommended outside clinical trials 1

Special Considerations

• For minor ischemic stroke or high-risk TIA, more recent evidence suggests dual antiplatelet therapy (aspirin plus clopidogrel) may be beneficial when initiated within 24-72 hours of symptom onset 5, 6
• The CHANCE trial showed that among patients with TIA or minor stroke treated within 24 hours, the combination of clopidogrel and aspirin was superior to aspirin alone for reducing 90-day stroke risk without increasing hemorrhage risk 6

Pitfalls to Avoid

• Delaying aspirin administration beyond 48 hours reduces its effectiveness in preventing early recurrent stroke 2, 3
• Using aspirin as a substitute for thrombolytic therapy in eligible patients 1, 7
• Administering aspirin within 24 hours of thrombolytic therapy due to increased bleeding risk 1