Should dual antiplatelet therapy be started after a transient ischemic attack?

Dual Antiplatelet Therapy After TIA

For patients with high-risk TIA (ABCD² score ≥4), dual antiplatelet therapy with aspirin plus clopidogrel should be initiated within 24 hours of symptom onset and continued for exactly 21 days, followed by transition to single antiplatelet therapy indefinitely. 1

Patient Selection Criteria

High-risk TIA patients eligible for DAPT must meet ALL of the following:

• ABCD² score ≥4 1, 2
• Presentation within 24 hours of symptom onset (benefit extends to 72 hours but diminishes) 1, 2
• Non-cardioembolic mechanism confirmed 1, 2
• Intracranial hemorrhage ruled out on CT or MRI 1, 2
• No recent IV alteplase within preceding 24 hours 1

Loading and Maintenance Protocol

Day 1 Loading Doses (administered immediately after eligibility confirmation):

• Clopidogrel 300 mg (acceptable range 300–600 mg) 1, 2
• Aspirin 160–325 mg 1, 2

Days 2–21 Maintenance Doses:

• Clopidogrel 75 mg once daily 1, 2
• Aspirin 75–100 mg once daily 1, 2

After Day 21:

• Switch to single antiplatelet therapy (aspirin 75–100 mg daily OR clopidogrel 75 mg daily) indefinitely 1, 2

Evidence Supporting 21-Day Duration

The 21-day DAPT regimen reduces recurrent ischemic stroke by 32% (RR 0.68,95% CI 0.55–0.83) compared to aspirin alone, with a number needed to treat of 67–91. 1, 3 Major bleeding increases modestly from 0.4% to 0.9% (RR 1.88–2.22), yielding a number needed to harm of 113–258. 1, 3, 4

Critical timing consideration: Maximal benefit occurs when DAPT is started within 12–24 hours of symptom onset; efficacy diminishes progressively when initiated between 24–72 hours. 1, 2

Absolute Contraindications to DAPT

Do NOT initiate DAPT if any of the following are present:

• Intracranial hemorrhage not excluded on neuroimaging 1, 2
• Moderate-to-severe stroke (NIHSS >3) 1, 5
• Low-risk TIA (ABCD² <4) 1, 5
• Presentation >72 hours after symptom onset 1, 2
• Active major bleeding or severe thrombocytopenia 1
• Severe renal impairment (CrCl <30 mL/min) 1
• Recent IV alteplase within 24 hours 1

Common Pitfalls to Avoid

Never extend DAPT beyond 21–30 days in routine TIA management, as prolonged therapy (>90 days) increases major bleeding risk 2.4-fold (RR 2.42,95% CI 1.37–4.30) without additional stroke prevention benefit. 1, 2, 3

Never delay initiation beyond 24 hours when eligibility criteria are met; the hazard ratio for stroke prevention is 0.68–0.75 when started within 12–24 hours but increases to 0.85 when delayed to 24–48 hours. 1

Never use DAPT as a substitute for anticoagulation in cardioembolic TIA (e.g., atrial fibrillation); oral anticoagulation is superior in this population. 1, 2

Special Populations

For patients with dysphagia or impaired swallowing:

• Administer clopidogrel 75 mg + aspirin 81 mg via enteral feeding tube, OR
• Use aspirin 325 mg rectal suppository as alternative 1, 2

For patients with severe renal impairment (CrCl <30 mL/min):

• Use aspirin monotherapy only (loading 160–325 mg, then 75–100 mg daily)
• Clopidogrel is contraindicated due to metabolite accumulation and heightened bleeding risk 1

Long-Term Management After 21 Days

After completing the 21-day DAPT course, transition to indefinite single antiplatelet therapy with one of the following options 1, 2:

• First-line: Aspirin 75–100 mg daily 1, 2
• Alternative (if aspirin intolerant): Clopidogrel 75 mg daily 1, 2
• Alternative regimen: Aspirin 25 mg + extended-release dipyridamole 200 mg twice daily 1, 2