For a patient with a stroke and a National Institutes of Health Stroke Scale (NIHSS) score of 13, how long should aspirin (acetylsalicylic acid) and clopidogrel be maintained?

Dual Antiplatelet Therapy Duration for Stroke with NIHSS 13

For a patient with an NIHSS score of 13, dual antiplatelet therapy with aspirin and clopidogrel should NOT be used; instead, aspirin monotherapy (160-325 mg loading dose, then 81-325 mg daily) should be initiated immediately and continued indefinitely. 1

Why Dual Antiplatelet Therapy Does Not Apply Here

The critical distinction is stroke severity. Dual antiplatelet therapy with clopidogrel plus aspirin is specifically indicated only for:

• Minor stroke (NIHSS 0-3) or
• High-risk TIA (ABCD2 score ≥4) 1

An NIHSS score of 13 represents a moderate-to-severe stroke, which falls well outside the eligibility criteria for dual antiplatelet therapy. 1

Evidence Supporting This Distinction

The Canadian Stroke Best Practice guidelines explicitly state that aspirin monotherapy was not associated with significant reduction in stroke recurrence among those with severe stroke, and the greatest benefit was seen in mild and moderately disabling strokes. 1

The 2021 AHA/ASA guidelines clearly restrict dual antiplatelet therapy to patients with NIHSS ≤3 (minor stroke) or NIHSS ≤5 in some protocols, emphasizing that this is not appropriate for moderate-to-severe strokes. 1

Correct Treatment Algorithm for NIHSS 13

Immediate Management (First 24-48 Hours)

• Loading dose: Aspirin 160-325 mg immediately after brain imaging excludes hemorrhage and dysphagia screening is passed 1
• Timing: Should be given within 48 hours of stroke onset for maximum benefit 1

Long-Term Maintenance (After Initial Loading)

• Aspirin 81-325 mg daily continued indefinitely or until an alternative antithrombotic regimen is started 1
• Alternative options include clopidogrel 75 mg daily or aspirin 25 mg plus extended-release dipyridamole 200 mg twice daily 1

Why Dual Therapy Would Be Harmful Here

Increased bleeding risk without proven benefit. The POINT and CHANCE trials that established dual antiplatelet therapy specifically excluded patients with moderate-to-severe strokes because:

• The risk of major hemorrhage increases significantly (HR 2.32,95% CI 1.10-4.87) 1
• For every 1000 patients treated with dual therapy for 90 days, 5 major hemorrhages would result 1
• The benefit demonstrated in trials was specific to minor strokes where the risk-benefit ratio favored dual therapy 1

Critical Timing Considerations

• If thrombolysis (alteplase) was given: Delay aspirin initiation until 24 hours post-thrombolysis 1
• If no thrombolysis: Start aspirin immediately after imaging excludes hemorrhage 1
• Anticoagulation: Should not be initiated urgently for moderate-to-severe strokes due to increased risk of intracranial hemorrhage 1

Common Pitfall to Avoid

Do not extrapolate dual antiplatelet therapy recommendations from minor stroke trials to moderate-to-severe strokes. The NIHSS threshold of ≤3 (or ≤5 in some protocols) is a hard cutoff based on safety data, not a suggestion. 1 Using dual therapy in a patient with NIHSS 13 would expose them to bleeding risk without evidence of benefit and contradicts guideline recommendations. 1