In a 77‑year‑old woman with cardiovascular disease and an old cerebral infarct on CT, should she be prescribed long‑term low‑dose aspirin or clopidogrel (Plavix) for secondary prevention?

Antiplatelet Therapy for Secondary Stroke Prevention in a 77-Year-Old Woman with Cardiovascular Disease

For this 77-year-old woman with cardiovascular disease and an old cerebral infarct, aspirin 75–100 mg daily is the recommended first-line antiplatelet therapy for long-term secondary stroke prevention, with clopidogrel 75 mg daily serving as an equally effective alternative if aspirin is not tolerated. 1, 2

Primary Recommendation: Single Antiplatelet Therapy

Long-term maintenance antiplatelet therapy should consist of a single agent—not dual therapy—for patients with a history of noncardioembolic ischemic stroke. 1, 3 The evidence strongly supports:

• Aspirin 75–100 mg once daily as the first-line option for lifelong secondary prevention 1, 2
• Clopidogrel 75 mg once daily as an equally effective alternative, particularly beneficial in patients with diabetes or aspirin intolerance 1
• Aspirin 25 mg plus extended-release dipyridamole 200 mg twice daily as another acceptable alternative regimen 1, 2

Why Not Dual Antiplatelet Therapy Long-Term?

Dual antiplatelet therapy with aspirin plus clopidogrel is explicitly NOT recommended for routine long-term secondary prevention beyond 21–30 days after the acute event. 1, 3 The evidence is clear:

• Long-term dual therapy (beyond 90 days) significantly increases intracranial hemorrhage risk (hazard ratio 2.22–2.32) without additional stroke-prevention benefit 1
• The CHARISMA trial showed no benefit of adding clopidogrel to aspirin in stable patients with established cardiovascular disease, and actually suggested harm in some subgroups 4
• Major bleeding increases from 1.3% with aspirin alone to 1.7% with dual therapy, with a number needed to harm of 113–263 1, 3

Choosing Between Aspirin and Clopidogrel

Both aspirin and clopidogrel are equally effective for long-term secondary prevention, so the choice depends on patient-specific factors: 1, 2

Favor Clopidogrel 75 mg daily if:

• Diabetes mellitus is present—the CAPRIE trial subgroup analysis showed enhanced benefit of clopidogrel over aspirin in diabetic patients 1, 3, 5
• Aspirin intolerance or allergy exists 1
• History of aspirin-related gastrointestinal bleeding 1
• Peripheral arterial disease is present—clopidogrel showed superior outcomes in this population 1, 5

Favor Aspirin 75–100 mg daily if:

• No contraindications to aspirin exist and cost is a consideration 1, 2
• Patient preference for once-daily dosing with lower cost 2
• No diabetes or peripheral arterial disease 1

Critical Exclusion: Cardioembolic Stroke

Before prescribing antiplatelet therapy, you must rule out a cardioembolic source (particularly atrial fibrillation), because anticoagulation—not antiplatelet therapy—is required for cardioembolic stroke prevention. 1, 2

• If atrial fibrillation is present with CHA₂DS₂-VASc score ≥2 in males or ≥3 in females, oral anticoagulation (NOAC or warfarin) is mandatory instead of antiplatelet therapy 2
• If mechanical prosthetic heart valves are present, warfarin with INR target 3.0 (range 2.5–3.5) is required 2

Special Considerations for This 77-Year-Old Patient

Age alone does not alter the antiplatelet regimen. 1 However, at age 77:

• Bleeding risk assessment is important—check for history of gastrointestinal bleeding, renal function (creatinine clearance), and concurrent anticoagulation needs 1, 2
• Proton pump inhibitor prophylaxis should be considered if gastrointestinal bleeding risk is elevated 2
• Monitor for signs of bleeding (gastrointestinal, intracranial) during follow-up 1

Dosing Algorithm

For aspirin:

• Maintenance dose: 75–100 mg once daily indefinitely 1, 2
• No loading dose is needed for chronic secondary prevention 2

For clopidogrel:

• Maintenance dose: 75 mg once daily indefinitely 1, 2
• No loading dose is needed for chronic secondary prevention 2, 3

Common Pitfalls to Avoid

• Never continue dual antiplatelet therapy (aspirin + clopidogrel) beyond 30 days unless a separate cardiac indication exists (e.g., recent drug-eluting stent placement) 1, 3
• Never use aspirin doses above 325 mg daily for maintenance therapy, as this increases bleeding risk without improving cardiovascular outcomes 1, 2
• Never discontinue antiplatelet therapy after the acute phase unless switching to anticoagulation for cardioembolic etiology 2
• Never assume "old infarct" means no need for secondary prevention—lifelong antiplatelet therapy is required to prevent recurrent events 1, 2

Monitoring and Follow-Up

No routine laboratory monitoring is required specifically for aspirin or clopidogrel therapy. 6, 5 However:

• Monitor for signs of bleeding (gastrointestinal, intracranial, other) at each visit 1
• Check complete blood count if bleeding symptoms develop 6
• Reassess cardiovascular risk factors (blood pressure, lipids, diabetes control) regularly 1

Evidence Quality

This recommendation is supported by Class I, Level A evidence from multiple large randomized controlled trials including the Antithrombotic Trialists' Collaboration meta-analyses, CAPRIE trial (19,185 patients), and recent stroke prevention guidelines from the American Heart Association/American Stroke Association. 1, 5, 7