What dose of aspirin (acetylsalicylic acid) is recommended for a patient with an abnormal calcium score, specifically coronary artery calcium (CAC)?

Aspirin Dosing for Abnormal Coronary Artery Calcium Score

For patients with an abnormal coronary artery calcium (CAC) score, a daily aspirin dose of 81 mg (range 75-100 mg) is recommended if they do not have high bleeding risk. 1

Aspirin Recommendations Based on CAC Score

CAC Score ≥100

• Patients with CAC score ≥100 have favorable risk/benefit ratio for aspirin therapy 1, 2, 3
• Low-dose aspirin (81 mg daily) is recommended for these patients without bleeding contraindications 1, 2
• This recommendation is supported by multiple analyses showing net clinical benefit in this population 1, 3

CAC Score <100

• For patients with CAC score <100, aspirin therapy may not provide net benefit 1, 2
• Patients with CAC=0 may experience net harm from aspirin therapy due to bleeding risk outweighing cardiovascular benefit 2, 3

Aspirin Dosing Considerations

• The optimal daily aspirin dose for cardiovascular prevention is 75-100 mg 1
• In the U.S., the most common low-dose tablet is 81 mg 1
• Higher doses (>100 mg) do not provide additional cardiovascular protection but increase bleeding risk 1
• The ADAPTABLE trial showed no significant differences in cardiovascular outcomes between 81 mg and 325 mg daily doses, but substantial switching from higher to lower doses occurred 4

Special Considerations

• Age is an important factor:

  • Patients >70 years generally have greater bleeding risk than benefit with aspirin for primary prevention 1
  • Aspirin is not recommended for primary prevention in adults <50 years with diabetes and no other major ASCVD risk factors 1

• Bleeding risk assessment:

  • Evaluate for history of bleeding, anemia, renal disease, or concomitant medications that increase bleeding risk 1
  • Patients on oral anticoagulants should generally avoid aspirin for primary prevention 1

Clinical Algorithm for Aspirin Use with Abnormal CAC

1. For CAC score ≥100:

   • Prescribe aspirin 81 mg daily if no contraindications or high bleeding risk 1, 2, 3
   • Higher benefit observed in those with CAC >400 1

2. For CAC score 1-99:

   • Consider additional risk factors and bleeding risk 1, 2
   • Generally not recommended unless other high-risk features present 1, 3

3. For CAC score = 0:

   • Avoid aspirin therapy as risk likely outweighs benefit 1, 2, 3

Common Pitfalls to Avoid

• Using higher aspirin doses (>100 mg) does not provide additional cardiovascular protection but increases bleeding risk 1
• Failing to reassess bleeding risk periodically in patients on long-term aspirin therapy 1
• Prescribing aspirin for primary prevention without considering CAC score and overall cardiovascular risk 1, 2
• Not recognizing that aspirin for primary prevention has a narrow therapeutic window where benefits outweigh risks 2, 3