What is the role of aspirin (acetylsalicylic acid) in the prevention of cardiac disease?

Role of Aspirin in Prevention of Cardiac Disease

Aspirin therapy is strongly recommended for secondary prevention in all patients with established cardiovascular disease, while for primary prevention it should be considered only in adults at increased risk for coronary heart disease (CHD) where the benefits outweigh bleeding risks. 1, 2

Secondary Prevention (Established Cardiovascular Disease)

• Aspirin 75-100 mg daily is recommended as lifelong therapy for patients with previous myocardial infarction, revascularization, or significant obstructive coronary artery disease 2
• For patients with established cardiovascular disease, the benefits of aspirin therapy far outweigh the bleeding risks 2
• In patients with aspirin intolerance, clopidogrel 75 mg daily is recommended as an alternative 2
• Following coronary stenting, aspirin should be combined with a P2Y12 inhibitor (typically clopidogrel) for up to 6 months 2, 3

Primary Prevention (No Established Cardiovascular Disease)

• Decisions about aspirin therapy should take into account overall risk for CHD, including age, sex, diabetes, cholesterol levels, blood pressure, family history, and smoking 1
• Men older than 40 years, postmenopausal women, and younger persons with risk factors for CHD (e.g., hypertension, diabetes, smoking) may consider aspirin therapy 1
• The balance of benefits and harms is most favorable in high-risk persons (5-year risk ≥3% or 10-year risk ≥10%) 1, 2
• Meta-analysis of primary prevention trials showed that aspirin therapy reduced the risk for CHD by 28% but had no significant effects on total mortality or stroke 1

Risk Assessment and Patient Selection

• Tools that incorporate specific information on multiple risk factors provide more accurate estimation of cardiovascular risk than simply counting risk factors 1
• For hypertensive patients, aspirin 75-81 mg daily is recommended for primary prevention in those aged 50 years or older with controlled blood pressure (<150/90 mmHg) and target organ damage, diabetes, or 10-year cardiovascular risk >15% 2
• Aspirin is not recommended for primary prevention in persons at low risk of cardiovascular events 2
• Aspirin is not recommended for those with diabetes aged <50 years with no other major ASCVD risk factors 2

Dosing Considerations

• For both primary and secondary prevention, low-dose aspirin (75-100 mg daily) is recommended 2
• The most common low-dose tablet in the US is 81 mg 2
• Lower doses (75-100 mg) appear as effective as higher doses and may have fewer side effects 1

Adverse Effects and Risk Mitigation

• Aspirin increases rates of gastrointestinal bleeding (approximately 2-4 per 1000 middle-aged persons and 4-12 per 1000 older persons given aspirin for 5 years) 1
• Aspirin may increase rates of hemorrhagic strokes by a small amount (0-2 per 1000 persons given aspirin for 5 years) 1
• Risk factors for bleeding complications include older age, uncontrolled hypertension, and concomitant use of other NSAIDs or anticoagulants 1, 4
• Co-therapy with a proton pump inhibitor can decrease the risk of gastrointestinal injury and complications in high-risk patients 4

Special Populations

• In diabetic patients, aspirin (75-162 mg/day) may be reasonable for primary prevention in adults aged ≥50 years with at least one additional major risk factor 2
• Aspirin use in patients aged <21 years is contraindicated due to the risk of Reye syndrome 2
• Although older patients may derive greater benefits due to higher baseline risk, their bleeding risk is also higher 1

Clinical Decision-Making

• Discussions with patients should address both potential benefits (prevention of myocardial infarction) and harms (gastrointestinal and intracranial bleeding) 1
• Recent evidence from primary prevention trials has shown either no benefit or modest benefit on combined ischemic endpoints, with an increased risk of bleeding, leading to more conservative recommendations 5
• Despite clear guidelines, studies indicate suboptimal rates of appropriate aspirin use in both high-risk patients who would benefit and low-risk patients who should avoid it 6