What are the recommendations for aspirin (acetylsalicylic acid) therapy in patients at high risk of cardiovascular events?

Aspirin Therapy for Cardiovascular Disease Prevention

Low-dose aspirin (75-162 mg daily) is recommended for primary prevention in patients with diabetes aged 50-69 years who have a 10-year cardiovascular disease risk >10% and at least one additional cardiovascular risk factor, provided they have low bleeding risk. 1

Patient Selection for Aspirin Therapy

Primary Prevention

• High CVD Risk (≥10% 10-year risk):

  • Ages 40-59: Consider aspirin therapy (individualized decision) 2
  • Ages 50-69 with diabetes: Recommend aspirin if low bleeding risk 1
  • Additional risk factors to consider: family history of premature CVD, hypertension, dyslipidemia, smoking, chronic kidney disease/albuminuria 1

• Moderate CVD Risk (6-10% 10-year risk):

  • The American Heart Association and American Stroke Association suggest considering aspirin when benefits outweigh risks 1

• Not Recommended for:

  • Adults ≥60 years old (regardless of risk factors) 2
  • Patients <50 years with no significant cardiovascular risk factors 1
  • Patients with low CVD risk (<6% 10-year risk) 1

Secondary Prevention

• Strongly recommended for all patients with established cardiovascular disease 3
• Reduces risk of serious vascular events by approximately 25% in patients with prior occlusive vascular events 3

Dosage Recommendations

• Primary Prevention: 75-162 mg daily (most common US dose: 81 mg) 1
• Acute MI: Initial loading dose of 160-325 mg, followed by 75-150 mg daily 3
• Long-term Secondary Prevention: 75-150 mg daily is as effective as higher doses 3

Benefits of Aspirin Therapy

Primary Prevention

• Reduces risk of coronary heart disease by 28% 4
• Reduces risk of first MI by 32% 3
• Reduces cardiovascular events by 12% (8.5% vs 9.6%) 1

Secondary Prevention

• Reduces serious vascular events by 25% 3
• Reduces risk of cardiovascular events by 21% 5
• Reduces nonfatal MI by 26% 5
• Reduces stroke by 25% 5
• Reduces all-cause mortality by 13% 5

Risks and Contraindications

Bleeding Risk

• Increases major bleeding risk by 29-48% 1
• Major GI bleeding episodes: 2-4 per 1,000 middle-aged individuals and 4-12 per 1,000 older individuals given aspirin for 5 years 4
• Hemorrhagic stroke risk increases by 0-2 per 1,000 persons over 5 years 4

Absolute Contraindications

• Active peptic ulcer disease
• History of aspirin allergy
• Severe liver disease
• Bleeding disorders
• Pediatric patients <21 years (risk of Reye syndrome) 1

Relative Contraindications

• History of GI bleeding/ulcers
• Age >70 years
• Concurrent anticoagulant or NSAID use
• Uncontrolled hypertension 1

Risk-Benefit Assessment

For every 1,000 patients treated for 33 months:

• 33 cardiovascular events prevented
• 12 nonfatal MIs prevented
• 25 nonfatal strokes prevented
• 14 deaths prevented
• 9 major bleeding events caused 5

Special Considerations

• Aspirin should be an adjunct, not an alternative, to managing other cardiovascular risk factors 3
• Abrupt discontinuation in patients with established CVD increases risk of cardiovascular events 1
• Concurrent use with NSAIDs or anticoagulants significantly increases bleeding risk 1
• Ibuprofen may block aspirin's cardioprotective effects when taken together 1
• For patients with documented aspirin allergy, clopidogrel (75 mg/day) should be used instead 1

Common Pitfalls

1. Overuse in low-risk patients: Aspirin has no net benefit in adults ≥60 years for primary prevention 2
2. Inadequate risk assessment: Failure to calculate 10-year CVD risk before recommending aspirin
3. Overlooking bleeding risk factors: Always assess bleeding risk alongside cardiovascular risk
4. Inappropriate dosing: Higher doses (>325 mg) increase bleeding risk without additional cardiovascular benefit 3
5. Discontinuing aspirin in secondary prevention: Benefits clearly outweigh risks in established CVD 1

Aspirin therapy decisions should be based on a careful assessment of both cardiovascular and bleeding risks, with clear evidence supporting its use in secondary prevention and more selective use in primary prevention based on age and risk factors.