When is aspirin indicated?

Aspirin Indications in Clinical Practice

Aspirin is indicated primarily for secondary prevention in patients with established cardiovascular disease, including prior myocardial infarction, stroke, or coronary revascularization, and may be considered for primary prevention only in select high-risk individuals after careful risk-benefit assessment.

Secondary Prevention Indications

• Aspirin 75-100 mg daily is strongly recommended for patients with a previous myocardial infarction (MI) or revascularization as lifelong therapy after an initial period of dual antiplatelet therapy (DAPT) 1
• Aspirin 75-100 mg daily is recommended for patients with definitive evidence of significant obstructive coronary artery disease (CAD) on imaging 1
• Aspirin therapy (75-162 mg/day) is recommended as a secondary prevention strategy in patients with diabetes who have a history of atherosclerotic cardiovascular disease 1
• Following coronary stenting, aspirin 75-100 mg daily is recommended in combination with clopidogrel for up to 6 months as the default antithrombotic strategy in patients with no indication for oral anticoagulation 1
• Aspirin (75-162 mg/day) is indicated for patients who have survived a prior occlusive vascular event, including MI, transient ischemic attacks, occlusive stroke, unstable and stable angina, percutaneous coronary interventions, and coronary artery bypass graft 2

Primary Prevention Indications

• Aspirin may be considered as a primary prevention strategy for adults with diabetes and no previous history of vascular disease who are at increased atherosclerotic cardiovascular disease (ASCVD) risk 1
• For primary prevention in diabetic patients, aspirin (75-162 mg/day) may be reasonable for both men and women aged ≥50 years with at least one additional major risk factor (family history of premature ASCVD, hypertension, dyslipidemia, smoking, or chronic kidney disease/albuminuria) who are not at increased risk of bleeding 1
• Aspirin (81 mg daily or 100 mg every other day) can be useful for prevention of a first stroke among women whose risk is sufficiently high for the benefits to outweigh the risks associated with treatment 1
• Aspirin is recommended for primary prevention in persons whose 10-year risk of cardiovascular events is 6-10% when benefits are likely to outweigh risks 1

Contraindications and Situations Where Aspirin is Not Indicated

• Aspirin is not recommended for primary prevention in persons at low risk of cardiovascular events 1
• Aspirin is not recommended for primary prevention in persons with diabetes or diabetes plus asymptomatic peripheral artery disease in the absence of other established cardiovascular disease 1
• Aspirin is not recommended for those at low risk of ASCVD (such as men and women aged <50 years with diabetes with no other major ASCVD risk factors) as the low benefit is likely outweighed by bleeding risks 1
• Aspirin use in patients aged <21 years is contraindicated due to the associated risk of Reye syndrome 1
• Aspirin should be used with caution during the last 3 months of pregnancy unless definitely directed by a doctor, as it may cause problems in the unborn child or complications during delivery 3

Dosing Considerations

• For secondary prevention, aspirin doses of 75-100 mg daily are recommended 1
• For acute coronary syndromes, a loading dose of 162-325 mg is recommended, followed by a maintenance dose of 75-100 mg daily 4, 5
• In acute myocardial infarction and acute occlusive stroke, a loading dose of 162.5-325 mg is necessary to achieve a rapid clinical antithrombotic effect 5
• For long-term treatment, daily doses of 75-325 mg aspirin are sufficient for prevention of cardiovascular disease 5
• The most common low-dose tablet in the US is 81 mg 1

Special Considerations

• In patients with aspirin intolerance, clopidogrel 75 mg daily is recommended as an alternative 1
• Dual antiplatelet therapy (with low-dose aspirin and a P2Y12 inhibitor) is reasonable for a year after an acute coronary syndrome 1, 4
• For patients with unstable angina or non-Q-wave MI, a combination of clopidogrel 75 mg and aspirin 75-100 mg is recommended 1
• The risk of major bleeding with aspirin therapy is approximately 1-2 cases per 1,000 patient-years of treatment 6
• Patients with uncontrolled hypertension and concomitant use of other nonsteroidal anti-inflammatory agents or anticoagulants have increased risk of serious bleeding 1, 4

Risk-Benefit Assessment

• For patients with established cardiovascular disease, the benefits of aspirin therapy far outweigh the bleeding risks 1
• In primary prevention, the balance of benefits and risks is most favorable in high-risk persons (five-year risk greater than 3%) 1
• For patients over age 70 years without established cardiovascular disease, the balance appears to have greater risk than benefit 1
• In adults with risk of ASCVD >1% per year, the number of cardiovascular events prevented will be similar or greater than the number of bleeding events induced 4