When is Dual Antiplatelet Therapy (DAPT) used for acute ischemic stroke?

Dual Antiplatelet Therapy for Acute Ischemic Stroke

Dual antiplatelet therapy (DAPT) with aspirin plus clopidogrel should be used for 21-30 days in patients with minor ischemic stroke (NIHSS 0-3) or high-risk TIA who present within 24-72 hours of symptom onset, followed by antiplatelet monotherapy indefinitely. 1, 2

Patient Selection for DAPT

DAPT is indicated for:

• Patients with minor ischemic stroke (NIHSS 0-3) 1
• High-risk TIA patients (ABCD2 score ≥4 or meeting "very high-risk" criteria) 1, 2
• Non-cardioembolic etiology 1, 2
• Presentation within 24-72 hours of symptom onset 1, 3

DAPT is contraindicated in:

• Patients who received thrombolysis (delay antiplatelet therapy until 24-hour post-thrombolysis scan excludes hemorrhage) 1
• Moderate to severe stroke 2
• High bleeding risk 2
• Cardioembolic stroke 1

DAPT Regimen

1. Initial loading doses:

   • Aspirin: 160-300 mg loading dose
   • Clopidogrel: 300-600 mg loading dose (300 mg minimum) 1, 2

2. Maintenance doses:

   • Aspirin: 81-100 mg daily
   • Clopidogrel: 75 mg daily 1, 2

3. Duration:

   • Continue DAPT for 21-30 days only 1, 2
   • Switch to single antiplatelet therapy (aspirin OR clopidogrel) after 21-30 days and continue indefinitely 1

Timing of Initiation

• Start DAPT as soon as possible after brain imaging confirms absence of hemorrhage 1
• Ideally within 12-24 hours of symptom onset 1, 2
• DAPT should be started prior to discharge from the emergency department 1
• Recent evidence shows benefit even when started within 72 hours of symptom onset 3

Evidence Supporting Short-Term DAPT

Meta-analyses of randomized controlled trials demonstrate that short-term DAPT initiated early after minor stroke or high-risk TIA:

• Reduces risk of recurrent ischemic stroke by 32% (RR 0.68; 95% CI: 0.55-0.83) 1, 4
• Reduces risk of total recurrent stroke by 31% (RR 0.69; 95% CI: 0.58-0.85) 2, 4

However, DAPT is associated with:

• Increased risk of major bleeding (RR 1.88; 95% CI: 0.93-3.83) 1, 4
• For every 1000 patients treated with DAPT for 21-30 days, approximately 15 ischemic strokes are prevented at the cost of 5 major hemorrhages 1

Special Considerations

1. Patients with high-grade carotid stenosis requiring urgent intervention:

   • Consult with the interventionalist/surgeon regarding antiplatelet management
   • Consider aspirin monotherapy instead of DAPT if carotid endarterectomy is planned urgently to reduce perioperative bleeding risk 1

2. Patients at higher risk of GI bleeding:

   • Consider GI protection while on DAPT 1

3. Long-term DAPT (>90 days):

   • Not recommended due to increased bleeding risk without additional benefit in stroke reduction 1
   • Long-term studies show DAPT beyond 90 days significantly increases major bleeding (RR 2.42; 95% CI: 1.37-4.30) without significant reduction in recurrent stroke 1

4. Patients with dysphagia:

   • ASA (80 mg daily) and clopidogrel (75 mg daily) may be given by enteral tube
   • Alternatively, ASA can be given by rectal suppository (325 mg daily) 1

Conclusion

The evidence strongly supports short-term DAPT (21-30 days) for patients with minor stroke or high-risk TIA when initiated within 24-72 hours of symptom onset, followed by long-term antiplatelet monotherapy. This approach provides optimal balance between reducing recurrent stroke risk and minimizing bleeding complications.