What is the role of aspirin in managing cardiovascular disease?

Why Take Aspirin if You Have Cardiovascular Disease

If you have established cardiovascular disease (prior heart attack, stroke, coronary revascularization, or significant coronary artery blockages), you should take aspirin 75-162 mg daily for life because it reduces your risk of another heart attack, stroke, or cardiovascular death by approximately 21-26%, and these benefits far outweigh the bleeding risks. 1, 2

The Evidence for Secondary Prevention

For patients with documented atherosclerotic cardiovascular disease, aspirin provides substantial mortality and morbidity benefits that clearly exceed bleeding risks 1:

• Cardiovascular event reduction: Aspirin reduces serious vascular events (heart attack, stroke, cardiovascular death) by 21% in patients with stable cardiovascular disease 3
• Heart attack prevention: Nonfatal myocardial infarction risk decreases by 26% 3
• Stroke prevention: Nonfatal stroke risk decreases by 25% 3
• Mortality benefit: All-cause mortality decreases by 13% 3

The American Diabetes Association and European Society of Cardiology both give aspirin for secondary prevention their highest level of recommendation (Class A evidence) 1, 2. This is based on decades of consistent data from over 212,000 patients in randomized trials showing that aspirin prevents approximately 25% of serious vascular events in those who have survived a prior cardiovascular event 4.

Practical Numbers: What This Means for You

Treating 1,000 patients with established cardiovascular disease with aspirin for approximately 3 years prevents 3:

• 33 cardiovascular events
• 12 nonfatal heart attacks
• 25 nonfatal strokes
• 14 deaths

This comes at the cost of causing 9 major bleeding events 3. The benefit-to-harm ratio is approximately 4:1 in favor of treatment 3.

Optimal Dosing

Use aspirin 75-100 mg daily (81 mg is the standard U.S. formulation) 1, 2, 5. This dose range provides equivalent cardiovascular protection to higher doses while significantly reducing bleeding complications 1, 2:

• The ADAPTABLE trial demonstrated no difference in cardiovascular events or bleeding between 81 mg and 325 mg daily doses in patients with established cardiovascular disease 1
• Doses above 162 mg increase bleeding risk without additional cardiovascular benefit 1, 6
• Even doses as low as 75 mg daily completely inhibit platelet thromboxane production, the mechanism by which aspirin prevents clots 7

Duration of Therapy

Aspirin should be continued lifelong after any initial period of dual antiplatelet therapy (aspirin plus a second agent like clopidogrel) 2, 5. After coronary stenting, you typically take dual antiplatelet therapy for 6-12 months, then transition to aspirin alone indefinitely 1, 2.

When Aspirin Cannot Be Used

If you have a documented aspirin allergy, clopidogrel 75 mg daily should be substituted 1, 2. This is the only acceptable alternative for patients requiring antiplatelet therapy who cannot tolerate aspirin 1.

Common Pitfalls to Avoid

Do not stop aspirin without consulting your cardiologist, even if you develop minor gastrointestinal symptoms 6. The cardiovascular risks of discontinuation far exceed the risks of most bleeding complications in secondary prevention 1:

• Upper gastrointestinal bleeding occurs in approximately 0.6% of patients annually (relative risk 2.6 compared to no aspirin) 6
• If you have risk factors for bleeding (prior peptic ulcer, age >70, H. pylori infection, concurrent NSAIDs or anticoagulants), you should receive a proton pump inhibitor for gastric protection rather than stopping aspirin 6
• Enteric-coated or buffered aspirin preparations do not reduce bleeding risk 1, 6

Do not use aspirin as monotherapy immediately after an acute coronary syndrome (heart attack or unstable angina) 1, 2. You require dual antiplatelet therapy (aspirin plus a P2Y12 inhibitor like clopidogrel, ticagrelor, or prasugrel) for at least one year 1.

Why Secondary Prevention Differs from Primary Prevention

The recommendation for aspirin in established cardiovascular disease is far stronger than for primary prevention (preventing a first event) because 1:

• Your baseline risk of recurrent events is much higher (typically >10% over 10 years)
• The absolute number of events prevented far exceeds the number of bleeding complications induced
• The mortality benefit is clearly established in secondary prevention but not in primary prevention 4, 8

For patients over age 70 without established cardiovascular disease, aspirin for primary prevention causes more harm than benefit 1. However, this age-related bleeding risk does not apply to secondary prevention—if you have established cardiovascular disease, aspirin remains beneficial regardless of age 1, 2.

Special Considerations for High-Risk Patients

If you have had a recent acute coronary syndrome or coronary intervention with high ischemic risk and low bleeding risk, long-term dual antiplatelet therapy (aspirin plus a P2Y12 inhibitor) should be considered beyond the standard 12-month period 1. Additionally, for patients with stable coronary or peripheral artery disease and low bleeding risk, combination therapy with aspirin plus low-dose rivaroxaban (2.5 mg twice daily) should be considered to prevent major adverse limb and cardiovascular events 1.