What are the indications to start antiplatelet therapy?

Indications to Start Antiplatelet Therapy

All patients with acute ischemic stroke or TIA who do not require anticoagulation should receive antiplatelet therapy immediately after intracranial hemorrhage is excluded on brain imaging. 1

Acute Ischemic Stroke and TIA

Standard Acute Stroke Management

• Immediate aspirin loading: Give at least 160 mg of aspirin as a one-time loading dose after brain imaging excludes intracranial hemorrhage and dysphagia screening is passed 1
• Continue maintenance therapy: ASA 81-325 mg daily should be continued indefinitely or until an alternative antithrombotic regimen is started 1
• Timing exception for thrombolysis: In patients receiving alteplase, delay antiplatelet initiation until after the 24-hour post-thrombolysis scan excludes intracranial hemorrhage 1

High-Risk TIA or Minor Stroke (Dual Antiplatelet Therapy)

For very high-risk TIA (ABCD2 score >4) or minor stroke (NIHSS 0-3) of non-cardioembolic origin, dual antiplatelet therapy with clopidogrel plus aspirin should be initiated within 24 hours (ideally within 12 hours) and continued for 21-30 days only. 1

Loading doses:

• Clopidogrel: 300-600 mg (300 mg based on CHANCE trial, 600 mg based on POINT trial) 1
• Aspirin: 160 mg 1

Maintenance regimen:

• Aspirin 81 mg daily + Clopidogrel 75 mg daily for 21-30 days 1
• After 21-30 days, switch to monotherapy (aspirin or clopidogrel alone) indefinitely 1

Rationale for limited duration: The POINT trial demonstrated that for every 1000 patients treated with dual antiplatelet therapy for 90 days, 15 ischemic strokes would be prevented but 5 major hemorrhages would result (ischemic stroke reduction: 4.6% vs 6.3%, HR 0.72; major hemorrhage increase: 0.9% vs 0.4%, HR 2.32) 1

Alternative dual therapy option:

• Aspirin 75-100 mg daily + Ticagrelor 90 mg twice daily for 30 days (loading: aspirin 300-325 mg + ticagrelor 180 mg) 1

Long-Term Secondary Prevention (Non-Cardioembolic)

For patients with non-cardioembolic ischemic stroke or TIA who do not require anticoagulation, long-term single antiplatelet therapy is indicated: 1

• Aspirin 81-325 mg daily, OR
• Clopidogrel 75 mg daily, OR
• Aspirin + dipyridamole 25/200 mg daily 1

Intracranial Atherosclerotic Disease (50-99% stenosis)

• Dual antiplatelet therapy is appropriate medical therapy for moderate to high-grade intracranial atherosclerotic stenosis 1
• Angioplasty and stenting is NOT recommended 1

Special Populations and Circumstances

After Intracerebral Hemorrhage (ICH)

In patients with ICH who had been taking antiplatelet agents for prevention of vascular events and have a history of major adverse cardiovascular events (MACE), resuming antiplatelet therapy may be reasonable beyond 24 hours after ICH symptom onset. 1

• This decision requires individualized risk-benefit assessment considering baseline risks of recurrent ICH versus occlusive vascular events 1
• Evidence level is B; guidelines are permissive but cannot make strong recommendations 1
• Strong indication to start: ICH associated with antithrombotic use + history of MACE + no atrial fibrillation 1
• Strong indication to avoid: ICH not associated with antithrombotic use (e.g., recurrent lobar ICH, major extracranial hemorrhage) 1

Dysphagic Patients

• ASA 80 mg daily and clopidogrel 75 mg daily may be given by enteral tube 1
• ASA by rectal suppository 325 mg daily is an alternative 1

Pediatric Patients

• Initial treatment with anticoagulation (heparin) or aspirin at established pediatric dosing should be considered until cervical artery dissection and intracardiac thrombus are excluded 1
• If neither is present, switch to acute aspirin therapy at dose of 1-5 mg/kg 1

Urgent Surgical Considerations

For patients with high-risk TIA or minor stroke caused by high-grade carotid stenosis who are candidates for urgent carotid endarterectomy, aspirin monotherapy rather than dual antiplatelet therapy may be appropriate to reduce perioperative bleeding risk. 1

Critical Pitfalls to Avoid

• Do NOT continue dual antiplatelet therapy beyond 21-30 days in minor stroke/high-risk TIA patients, as bleeding risk accumulates over time without additional ischemic benefit 1
• Do NOT start antiplatelet therapy before brain imaging excludes hemorrhage 1
• Do NOT use prasugrel in patients with history of TIA or stroke (FDA contraindication) 2
• Consider GI protection in patients at higher risk of GI bleeding when on dual antiplatelet therapy 1
• Counsel patients explicitly that dual therapy is temporary (21-30 days only) and they must resume monotherapy afterward 1