Why is she prescribed low-dose aspirin for cardiovascular event prevention given her history of atherosclerotic disease and multiple risk factors?

Why She Is Taking Aspirin

She is taking low-dose aspirin (75-162 mg daily) because she has established atherosclerotic cardiovascular disease, which makes aspirin a strongly recommended secondary prevention therapy with proven mortality and morbidity benefits that far outweigh bleeding risks. 1, 2

Secondary Prevention: The Core Indication

For patients with a documented history of atherosclerotic disease—including prior myocardial infarction, stroke, revascularization procedures, or significant coronary artery stenosis—aspirin therapy is a Grade A recommendation with robust evidence of benefit. 1, 2

• Aspirin reduces major cardiovascular events by approximately 25% in high-risk secondary prevention patients, including reductions in non-fatal MI by one-sixth, non-fatal stroke by one-quarter, and cardiovascular death by one-sixth. 3
• The American Diabetes Association and European Society of Cardiology both strongly endorse aspirin 75-162 mg daily as lifelong therapy for all patients with established atherosclerotic cardiovascular disease. 1, 2
• In secondary prevention, the benefits of aspirin therapy far outweigh the bleeding risks, unlike the more controversial role in primary prevention. 1, 2

Optimal Dosing for Secondary Prevention

The recommended dose range is 75-162 mg daily, with 75-100 mg being optimal. 2, 4

• The most common U.S. formulation is 81 mg daily, which provides full cardiovascular protection while minimizing gastrointestinal bleeding risk. 1, 2
• The ADAPTABLE trial demonstrated no difference in cardiovascular events or bleeding between 81 mg and 325 mg daily doses, supporting use of the lower dose. 4
• Higher doses (>100 mg) increase gastrointestinal bleeding risk without proportional cardiovascular benefit. 4

Risk Factors That Amplify Her Need for Aspirin

If she has diabetes in addition to atherosclerotic disease, this further strengthens the indication. 1, 2

• Diabetic patients with established cardiovascular disease have a two- to fourfold increased risk of dying from cardiovascular complications, making antiplatelet therapy even more critical. 2
• The combination of hypertension and diabetes creates an intermediate-to-high cardiovascular risk profile that benefits from aspirin therapy. 2

Bleeding Risk Considerations in Her Case

While aspirin increases bleeding risk, this is acceptable in secondary prevention. 1, 4

• Major bleeding occurs at approximately 5 per 1,000 patients per year with aspirin therapy in real-world settings. 1, 4
• For adults with established ASCVD, the number of cardiovascular events prevented substantially exceeds the number of bleeding episodes induced, and these complications do not have equal effects on long-term health. 1
• Bleeding risk increases with age >70 years, uncontrolled hypertension, concurrent NSAIDs or anticoagulants, and history of gastrointestinal bleeding. 2, 4

Common Pitfalls to Avoid

• Do not discontinue aspirin in secondary prevention patients due to bleeding concerns unless there is active major bleeding or absolute contraindication—the cardiovascular risk of stopping far exceeds the bleeding risk of continuing. 1, 2
• Do not use unnecessarily high doses (>162 mg daily), which increase bleeding without additional cardiovascular benefit. 2, 4
• Ensure blood pressure is controlled before initiating or continuing aspirin, as uncontrolled hypertension amplifies bleeding risk. 2

Alternative Therapy if Aspirin Is Not Tolerated

• For patients with documented aspirin allergy, clopidogrel 75 mg daily should be substituted. 1, 2, 4
• Dual antiplatelet therapy (aspirin plus a P2Y12 inhibitor like clopidogrel) is reasonable for one year after an acute coronary syndrome and may have benefits beyond this period. 1, 2

Contrast with Primary Prevention

Unlike secondary prevention, aspirin for primary prevention (no prior cardiovascular events) remains controversial. 1, 2

• Recent trials (ARRIVE, ASPREE) found no benefit of aspirin for primary prevention in patients without diabetes or in the elderly, with increased bleeding risk. 1
• For primary prevention, aspirin is only considered in select high-risk patients (10-year ASCVD risk >10%, age ≥50 years with multiple risk factors) after careful shared decision-making. 2
• In patients over age 70 years without established cardiovascular disease, the balance favors harm over benefit. 1, 2