Aspirin Should NOT Be Started—Anticoagulation is Required
A 60-year-old female with a right MCA infarct due to cardioembolic stroke from atrial fibrillation requires oral anticoagulation, not aspirin, for secondary stroke prevention. Aspirin is substantially inferior to anticoagulation in this high-risk scenario and should not be used as monotherapy 1.
Why Anticoagulation is Mandatory
This patient has already suffered a cardioembolic stroke from AF, placing her in the highest risk category for recurrent stroke 1. Prior thromboembolism is classified as a "major" risk factor with stroke rates of 6.4-12% per year on aspirin alone 1, 2.
Anticoagulation reduces stroke risk by 67% compared to placebo, while aspirin reduces it by only 19-42% 1, 3. The European Atrial Fibrillation Trial definitively demonstrated the superiority of anticoagulation over aspirin for secondary stroke prevention in AF patients 1.
Direct oral anticoagulants (DOACs) are now first-line therapy over warfarin for non-valvular AF due to superior safety profiles and at least equivalent efficacy 4. Options include apixaban, rivaroxaban, dabigatran, or edoxaban 1, 4.
Timing of Anticoagulation After Acute Stroke
Anticoagulation should typically be initiated approximately 2 weeks after the acute ischemic stroke in the absence of hemorrhagic transformation 1.
For large cerebral infarctions, delaying anticoagulation initiation should be considered given the increased risk of hemorrhagic transformation 1.
Cerebral imaging (CT or MRI) must be performed before starting anticoagulation to exclude intracranial hemorrhage 1.
Why Aspirin is Inadequate
Aspirin provides only modest stroke protection (19% risk reduction) and is particularly ineffective against cardioembolic strokes, which tend to be more disabling than non-cardioembolic strokes 1, 5.
In elderly women specifically, the thromboembolic rate on aspirin remains unacceptably high at 10.4% per year 2. This patient at age 60 with prior stroke would have an annual stroke risk of approximately 6.4% on aspirin alone 2.
The bleeding risk with aspirin is similar to warfarin, especially in the elderly, negating the perceived safety advantage 1, 6.
Recommended Anticoagulation Strategy
Start a DOAC as first-line therapy 4:
- Apixaban 5 mg twice daily (or 2.5 mg twice daily if ≥2 of: age ≥80, weight ≤60 kg, creatinine ≥1.5 mg/dL) 4
- Alternative DOACs: rivaroxaban, dabigatran, or edoxaban 1, 4
If warfarin is used instead (e.g., due to cost or patient preference):
For patients who sustain stroke while on standard-intensity anticoagulation (INR 2.0-3.0), increase the target INR to 3.0-3.5 rather than adding aspirin 1.
Critical Pitfall to Avoid
Do not use aspirin alone in AF patients with prior stroke—this represents inadequate therapy and exposes the patient to unacceptably high recurrent stroke risk 1, 5. The only scenario where aspirin might be considered is if there is an absolute contraindication to all anticoagulants, but even then, the combination of aspirin plus clopidogrel is preferred over aspirin monotherapy 1.