When should Dual Antiplatelet Therapy (DAPT) be started in patients with ischemic stroke?

Timing of Dual Antiplatelet Therapy (DAPT) in Ischemic Stroke

DAPT with aspirin and clopidogrel should be initiated as early as possible, ideally within 12-24 hours of symptom onset in patients with minor ischemic stroke (NIHSS ≤3) or high-risk TIA (ABCD2 ≥4), after excluding intracranial hemorrhage on neuroimaging. 1

Patient Selection for DAPT

Appropriate Candidates:

• Minor ischemic stroke (NIHSS ≤3) 1
• Mild-moderate ischemic stroke (NIHSS ≤5) 1
• High-risk TIA (ABCD2 score ≥4) 1
• Non-cardioembolic stroke etiology 1
• After exclusion of intracranial hemorrhage on neuroimaging 1

Timing Considerations:

• Start DAPT as soon as possible after brain imaging confirms absence of hemorrhage 1
• Optimal window: within 12-24 hours of symptom onset 1
• Can be effective when started within 72 hours in patients with mild stroke or high-risk TIA of presumed atherosclerotic origin 2
• For patients receiving thrombolysis (alteplase), delay antiplatelet initiation until after the 24-hour post-thrombolysis scan has excluded intracranial hemorrhage 1

Dosing Protocol

Initial Loading Dose:

• Aspirin: 160-325 mg (single loading dose) 1
• Clopidogrel: 300 mg (per CHANCE trial) or 600 mg (per POINT trial) 1

Maintenance Dosing:

• Aspirin: 81 mg daily 1
• Clopidogrel: 75 mg daily 1

Duration of DAPT

• DAPT should be continued for 21 days (per CHANCE trial) to 30 days (per POINT trial) 1
• After completing the DAPT course, transition to long-term single antiplatelet therapy with either aspirin 81 mg daily or clopidogrel 75 mg daily 1

Alternative DAPT Regimen

For mild-moderate ischemic stroke (NIHSS ≤5) or high-risk TIA (ABCD2 ≥4):

• Aspirin 75-100 mg daily plus ticagrelor 90 mg twice daily 1
• Initial loading: aspirin 300-325 mg and ticagrelor 180 mg 1
• Duration: 30 days, then transition to single antiplatelet therapy 1

Special Considerations

Dysphagia:

• For patients with swallowing difficulties:
  • Rectal aspirin 325 mg daily or
  • Aspirin 81 mg daily via enteral tube or
  • Clopidogrel 75 mg daily via enteral tube 1

Bleeding Risk:

• Higher risk of major bleeding with DAPT (RR 2.22,95% CI 1.14-4.34) 3
• Consider GI protection in patients at higher risk of GI bleeding 1
• Short-duration DAPT (≤1 month) has better safety profile than longer DAPT regimens 4

Carotid Intervention:

• For patients with high-grade carotid stenosis who are candidates for urgent carotid endarterectomy or stenting, consult with the interventionalist/surgeon regarding appropriate antiplatelet regimen 1
• In some cases, aspirin monotherapy may be preferred over DAPT if urgent carotid endarterectomy is planned, to reduce perioperative bleeding risk 1

Clinical Benefits and Risks

Benefits:

• Reduced risk of recurrent stroke (RR 0.76,95% CI 0.68-0.83) 3
• Reduced risk of major adverse cardiovascular events (RR 0.76,95% CI 0.69-0.84) 3
• Effective in both anterior and posterior circulation infarcts 5

Risks:

• Increased risk of major bleeding (RR 1.90,95% CI 1.33-2.72) 4
• Increased risk of intracranial bleeding (RR 1.55,95% CI 1.20-2.01) 4

Key Pitfalls to Avoid

1. Delaying DAPT initiation beyond 24 hours in eligible patients
2. Continuing DAPT beyond the recommended 21-30 day period
3. Failing to transition to monotherapy after completing the DAPT course
4. Using DAPT in patients with cardioembolic stroke or when anticoagulation is indicated
5. Starting DAPT before excluding intracranial hemorrhage on neuroimaging
6. Neglecting to counsel patients about the limited duration of DAPT (21-30 days only)