Can antiplatelet therapy be initiated in a patient with vertebral artery dissection?

Antiplatelet Therapy in Vertebral Artery Dissection

Yes, antiplatelet therapy can and should be initiated in vertebral artery dissection—it is equally effective as anticoagulation and carries a lower bleeding risk, making it a reasonable first-line choice for most patients. 1, 2

Initial Antithrombotic Management

Both antiplatelet therapy and anticoagulation are recommended options for vertebral artery dissection, with equivalent efficacy in preventing recurrent stroke. 1, 2

Antiplatelet Regimen Options:

• Aspirin 81-325 mg daily as monotherapy 1, 2
• Clopidogrel 75 mg daily as an alternative 1, 2
• Either agent results in a stroke/death rate of approximately 2% at 3 months and 3.2% at 1 year 2

Treatment Duration:

• Continue antithrombotic therapy for at least 3-6 months 1, 2
• After the initial 3-6 month period, transition to long-term single antiplatelet therapy 2

Evidence Supporting Antiplatelet Use

The decision between antiplatelet therapy versus anticoagulation should be based on bleeding risk assessment, not efficacy differences:

• The CADISS trial demonstrated no significant difference between treatments (OR 0.335,95% CI 0.006-4.233; p=0.63), with only 2% overall stroke recurrence in both groups 3, 4
• Observational data from 370 patients showed similar event rates: 9.6% with antiplatelets versus 10.4% with anticoagulation for spontaneous dissection 5
• The actual risk of recurrent stroke is much lower than historically reported—only 2.4-2.5% at one year in randomized trial settings 3, 4

Critical Caveat: Intracranial Extension

Anticoagulation is contraindicated if there is intracranial extension of the dissection with subarachnoid hemorrhage risk. 2, 6

• Intracranial vertebrobasilar dissections carry higher rupture risk 2
• The risk of hemorrhagic transformation with antiplatelet therapy alone is low (<5%) 2
• Always confirm the location of dissection (extracranial vs intracranial) before initiating treatment using CTA, MRA, or catheter angiography 1, 2

Practical Algorithm

1. Confirm diagnosis with CTA or MRA to establish extracranial versus intracranial location 1, 2

2. Rule out intracranial extension and subarachnoid hemorrhage on neuroimaging 2, 6

3. For extracranial vertebral artery dissection:

   • Start aspirin 81-325 mg daily OR clopidogrel 75 mg daily immediately 1, 2
   • Continue for 3-6 months 1, 2
   • Transition to long-term single antiplatelet therapy thereafter 2

4. For intracranial dissection:

   • Antiplatelet therapy is preferred over anticoagulation due to bleeding risk 2, 5
   • Observational data shows 8.5% event rate with antiplatelets versus 15.4% with anticoagulation in intracranial dissection 5

5. Reserve anticoagulation for:

   • Patients with documented thrombus formation 2
   • Progressive symptoms despite antiplatelet therapy 2
   • Individual risk-benefit analysis favoring anticoagulation (e.g., low bleeding risk, high thrombotic burden) 1

Common Pitfalls to Avoid

• Do not delay treatment initiation—start antithrombotic therapy immediately once hemorrhage is excluded 2, 6
• Do not assume anticoagulation is superior—the CADISS trial definitively showed equivalence, and antiplatelet therapy avoids the bleeding risks of warfarin 3, 4
• Do not use anticoagulation in intracranial dissection without careful consideration of subarachnoid hemorrhage risk 1, 2
• Do not continue indefinite antithrombotic therapy beyond 3-6 months at full intensity—most dissections heal spontaneously, and long-term single antiplatelet therapy is sufficient 2

Prognosis

With appropriate antithrombotic treatment, the prognosis is favorable, with anatomic healing occurring in 72-100% of patients. 2

• Dissections that do not fully heal anatomically are not associated with increased recurrent stroke risk 2
• Good functional outcome (modified Rankin score ≤2) is achieved in approximately 75% of patients 7