What is a stroke and what is the role of antiplatelets (anti-platelet agents) in its management?

Stroke and the Role of Antiplatelet Therapy

Antiplatelet therapy, particularly aspirin 325 mg given within 24-48 hours of stroke onset, is recommended for most patients with acute ischemic stroke to reduce mortality and disability by preventing early recurrent stroke. 1

What is a Stroke?

A stroke is a sudden interruption in the blood supply to the brain, causing brain tissue damage due to lack of oxygen and nutrients. There are two main types:

1. Ischemic Stroke: Accounts for approximately 87% of all strokes 2

   • Caused by blockage of blood vessels supplying the brain
   • Results from either thrombosis (blood clot forming locally) or embolism (clot traveling from elsewhere)

2. Hemorrhagic Stroke:

   • Caused by bleeding into or around the brain tissue

Role of Antiplatelet Therapy in Stroke Management

Mechanism of Action

Antiplatelet agents work by:

• Preventing platelet activation and aggregation
• Reducing clot formation in cerebral arteries
• Decreasing risk of early recurrent ischemic events

Benefits of Antiplatelet Therapy

• Reduces early recurrent stroke risk 1
• Decreases stroke-related mortality and morbidity 1, 3
• For every 1000 people treated with aspirin, 13 people avoid death or dependency 3

Specific Antiplatelet Recommendations for Acute Stroke

1. First-line Treatment:

   • Aspirin 325 mg orally within 24-48 hours after stroke onset (Class I, Level of Evidence A) 1
   • Should be continued for secondary prevention

2. Important Limitations:

   • Aspirin should NOT be considered a substitute for intravenous rtPA (thrombolytic therapy) 1
   • Aspirin should NOT be given within 24 hours of thrombolytic therapy 1

3. Other Antiplatelet Agents:

   • Clopidogrel alone or in combination with aspirin is not recommended for acute ischemic stroke (Class III, Level of Evidence C) 1
   • Intravenous glycoprotein IIb/IIIa inhibitors (tirofiban, eptifibatide) should only be used in clinical trials (Class IIb, Level of Evidence C) 1

Secondary Stroke Prevention with Antiplatelets

After the acute phase, antiplatelet therapy is crucial for preventing recurrent strokes:

• Single antiplatelet therapy with aspirin or clopidogrel reduces recurrent stroke risk in non-cardioembolic ischemic stroke 2, 4

• Short-term dual antiplatelet therapy (aspirin plus clopidogrel or ticagrelor) for 21-30 days is more effective than single therapy for minor strokes or high-risk TIAs 2, 4

• For intracranial atherosclerotic disease, dual antiplatelet therapy for 90 days followed by aspirin monotherapy may be appropriate 2, 4

Clinical Pitfalls and Caveats

1. Bleeding Risk:

   • Antiplatelet therapy increases risk of hemorrhagic complications
   • Carefully assess bleeding risk, especially with dual therapy 2, 4

2. Timing Considerations:

   • Early initiation (within 48 hours) is critical for maximum benefit 1
   • Prolonged dual antiplatelet therapy beyond recommended duration increases bleeding risk without additional benefit 2, 4

3. Patient Selection:

   • Antiplatelet agents are primarily for non-cardioembolic strokes
   • For cardioembolic strokes (e.g., atrial fibrillation), anticoagulants are preferred 2, 5

4. Contraindications:

   • Active pathological bleeding
   • History of intracranial hemorrhage requires careful consideration 1, 6

By understanding the role of antiplatelet therapy in stroke management, clinicians can effectively reduce the risk of recurrent events and improve patient outcomes while minimizing potential complications.