What is the recommended dose of aspirin (acetylsalicylic acid) for patients with large Middle Cerebral Artery (MCA) strokes?

Aspirin Dosing for Large MCA Strokes

For patients with large middle cerebral artery (MCA) strokes, administer aspirin 160-325 mg as a loading dose within 24-48 hours after stroke onset (once hemorrhage is excluded), followed by 75-100 mg daily for maintenance therapy.

Acute Phase Management

Initial Loading Dose

• Administer 160-325 mg aspirin within 24-48 hours of symptom onset after brain imaging excludes intracranial hemorrhage 1, 2
• The 2018 AHA/ASA guidelines specifically recommend doses between 160-300 mg based on landmark clinical trials (CAST and IST) 1
• Aspirin should be chewed when possible for faster buccal absorption and onset of antiplatelet action 1
• For patients unable to swallow, use rectal or nasogastric administration 1

Critical Timing Considerations

• Do NOT delay aspirin for patients eligible for IV alteplase - aspirin is not a substitute for acute reperfusion therapy 1
• If IV thrombolysis is administered, delay aspirin for 24 hours after alteplase 1
• However, aspirin may be considered earlier in the presence of concomitant conditions where withholding treatment poses substantial risk 1

Maintenance Therapy

Long-Term Dosing

• Continue with 75-100 mg daily (uncoated, low-dose aspirin) indefinitely for secondary stroke prevention 1, 2
• This lower maintenance dose provides equivalent efficacy to higher doses (300-325 mg) but with significantly reduced bleeding risk 1
• The 75-100 mg dose exceeds the minimal effective threshold for platelet thromboxane A2 suppression while accounting for interindividual variability 1

Special Considerations for Large MCA Strokes

Hemorrhagic Transformation Risk

• Large MCA strokes carry higher risk of hemorrhagic transformation, making the timing of aspirin initiation particularly important 1
• Ensure brain imaging excludes hemorrhage before any aspirin administration 1, 2
• The 24-48 hour window allows time to assess stroke evolution and hemorrhagic risk 1

Alternative Antiplatelet Agents

• Clopidogrel alone or in combination with aspirin is NOT recommended for acute treatment of large territorial strokes 1
• Dual antiplatelet therapy (aspirin + clopidogrel) is reserved for minor strokes or high-risk TIA, not large MCA strokes 1, 2
• IV glycoprotein IIb/IIIa inhibitors (abciximab, eptifibatide, tirofiban) are potentially harmful and should not be used 1

Evidence Strength

The recommendation is based on Class I, Level A evidence from two large randomized trials:

• The Chinese Acute Stroke Trial (CAST) and International Stroke Trial (IST) collectively enrolled over 40,000 patients 1
• These trials demonstrated a small but statistically significant reduction in mortality and recurrent stroke when aspirin (160-300 mg) was initiated within 48 hours 1
• A Cochrane review confirmed these findings across multiple aspirin trials 1

Common Pitfalls to Avoid

• Do not use aspirin as a substitute for mechanical thrombectomy or IV thrombolysis in eligible patients 1
• Do not administer aspirin within 24 hours of IV alteplase unless compelling indications exist 1
• Do not use higher maintenance doses (>100 mg) long-term - they increase bleeding without improving efficacy 1
• Do not withhold aspirin in large strokes due to size concerns - the evidence supports use across all ischemic stroke severities 1