What are the indications for aspirin (acetylsalicylic acid) prophylaxis?

Aspirin Prophylaxis Indications

Aspirin prophylaxis is strongly recommended for secondary prevention of cardiovascular disease in patients with established atherosclerotic disease, while primary prevention should be limited to select high-risk individuals where benefits outweigh bleeding risks.

Secondary Prevention Indications

• Aspirin (75-100 mg daily) is definitively indicated for secondary prevention in patients with:

  • Acute myocardial infarction (150 mg daily in acute setting) 1
  • Prior myocardial infarction 1
  • Stable and unstable angina 1
  • Prior stroke or transient ischemic attack 1
  • Established atherosclerotic cardiovascular disease 1

• For patients with documented aspirin allergy who require antiplatelet therapy, clopidogrel (75 mg daily) should be used instead 1

• Dual antiplatelet therapy (aspirin plus P2Y12 inhibitor) is recommended for at least 1 year following acute coronary syndrome 1

Primary Prevention Indications

• Primary prevention with aspirin should be limited to individuals at high cardiovascular risk where benefits outweigh bleeding risks 1:

  • Persons with 10-year cardiovascular risk >10% may be considered for aspirin prophylaxis 1
  • Women >65 years of age with controlled blood pressure and high cardiovascular risk 1
  • Women with multiple cardiovascular risk factors (hypertension, hyperlipidemia, diabetes) 1

• Aspirin is NOT recommended for primary prevention in:

  • Low-risk individuals (Class III; Level of Evidence A) 1
  • Persons with diabetes without other high-risk conditions (Class III; Level of Evidence A) 1
  • Persons with diabetes and asymptomatic peripheral artery disease (ankle brachial index ≤0.99) without established cardiovascular disease 1
  • Adults >70 years of age due to increased bleeding risk 1
  • Adults <40 years of age due to insufficient evidence 1

Special Populations

• Patients with chronic kidney disease (estimated GFR <45 mL/min/1.73 m²) may benefit from aspirin for primary prevention 1

• Patients with high-risk antiphospholipid profile (triple-positive or double-positive antiphospholipid testing) should receive prophylactic aspirin (75-100 mg daily) 1

• Patients with systemic lupus erythematosus and high-risk antiphospholipid profile should receive prophylactic aspirin (75-100 mg daily) 1

Dosing Considerations

• Secondary prevention: 75-100 mg daily is the recommended maintenance dose 1, 2

  • For acute myocardial infarction, an initial loading dose of 162-325 mg is recommended 2

• Primary prevention: 75-100 mg daily when indicated 1

• Lower doses (75-100 mg) are preferred over higher doses (>100 mg) for long-term use to minimize bleeding risk while maintaining efficacy 1, 3

• Uncoated aspirin should be chewed when possible in acute settings for faster antiplatelet action 2

Risk-Benefit Assessment

• The main adverse effect is increased gastrointestinal bleeding risk (up to 5 per 1,000 per year in real-world settings) 1

• For adults with ASCVD risk >1% per year, the number of cardiovascular events prevented will be similar to or greater than bleeding events induced 1

• Risk factors for increased bleeding include:

  • Age >70 years 1
  • Uncontrolled hypertension 2
  • Concomitant use of other NSAIDs or anticoagulants 2
  • History of gastrointestinal bleeding 1

• The decision to use aspirin for primary prevention should carefully weigh cardiovascular risk against bleeding risk, with stronger consideration in those unable to achieve optimal control of other cardiovascular risk factors 1