What are the indications for daily aspirin (acetylsalicylic acid) therapy?

Indications for Daily Aspirin Therapy

Daily aspirin therapy is indicated for secondary prevention in patients with established cardiovascular disease, including prior myocardial infarction, stable and unstable angina, stroke, transient ischemic attack, and peripheral arterial disease, but is generally not recommended for primary prevention except in select high-risk individuals. 1

Secondary Prevention Indications

Established Cardiovascular Disease

• Coronary Artery Disease:

  • Prior myocardial infarction: 75-162 mg daily 1
  • Stable angina: 75-162 mg daily 1
  • Unstable angina: 75-162 mg daily 1
  • Post-coronary artery bypass grafting: 100-325 mg daily for 1 year 1
  • Post-percutaneous coronary intervention with stent placement: 75-162 mg daily in combination with a P2Y12 inhibitor 1

• Cerebrovascular Disease:

  • Prior ischemic stroke: 75-325 mg daily 1
  • Transient ischemic attack: 75-325 mg daily 1

• Peripheral Arterial Disease:

  • Symptomatic peripheral arterial disease: 75-325 mg daily 1
  • Critical limb ischemia: 75-325 mg daily 1
  • Post-peripheral revascularization: 75-325 mg daily 1

Acute Cardiovascular Events

• Acute Myocardial Infarction: Initial loading dose of 162-325 mg followed by 75-162 mg daily 1
• Acute Ischemic Stroke: 160-325 mg daily initially 2

Primary Prevention Indications

High Cardiovascular Risk Individuals

• 10-year cardiovascular risk ≥6-10%: Consider aspirin 75-162 mg daily if benefits outweigh bleeding risks 1
• Women ≥65 years with risk factors: Consider aspirin 81-100 mg daily 1

Diabetes Mellitus

• Diabetes with additional risk factors: Consider aspirin 75-162 mg daily in patients ≥50 years with at least one additional major risk factor (family history of premature ASCVD, hypertension, dyslipidemia, smoking, or chronic kidney disease) 1, 2
• Not recommended: For diabetic patients <50 years without additional risk factors 1, 2
• Generally not recommended: For diabetic patients >70 years due to increased bleeding risk 1, 2

Dosing Recommendations

Secondary Prevention

• Most conditions: 75-162 mg daily 1
• Acute myocardial infarction: 150 mg daily 1
• Post-coronary bypass: 100-325 mg daily 1

Primary Prevention

• When indicated: 75-162 mg daily, with 81 mg being the most common dose in the US 1, 2, 3

Contraindications and Caution

• Absolute contraindications: Known hypersensitivity to aspirin, active peptic ulcer disease, recent gastrointestinal bleeding
• Relative contraindications: History of gastrointestinal bleeding, concurrent use of anticoagulants or NSAIDs, uncontrolled hypertension, severe renal or hepatic disease
• Age <21 years: Contraindicated due to risk of Reye syndrome 1
• Pregnancy: Use with caution, especially in third trimester

Clinical Considerations

• The benefit of aspirin therapy must be weighed against the risk of bleeding, particularly gastrointestinal and intracranial hemorrhage 4, 5
• Higher doses (>100 mg daily) do not provide additional cardiovascular benefit but increase bleeding risk 6, 3
• For patients at high risk of gastrointestinal bleeding who require aspirin, consider adding a proton pump inhibitor 2
• In patients requiring anticoagulation, aspirin should be used with caution and at the lowest effective dose 1

Special Populations

• Peripheral Arterial Disease: Evidence for aspirin benefit is less robust than for coronary disease, but still recommended for symptomatic disease 1, 7
• Aspirin Hypersensitivity: Consider desensitization or alternative antiplatelet therapy (e.g., clopidogrel 75 mg daily) 1
• Elderly (>70 years): Greater caution needed due to increased bleeding risk, especially for primary prevention 1

Aspirin remains a cornerstone of therapy for secondary prevention of cardiovascular events, with clear mortality and morbidity benefits that outweigh bleeding risks. For primary prevention, the decision should be based on careful assessment of individual cardiovascular risk versus bleeding risk.