Should a patient with atherosclerosis of the aorta and no other risk factors be on aspirin (acetylsalicylic acid) therapy?

Aspirin Therapy for Patients with Atherosclerosis of the Aorta

Patients with atherosclerosis of the aorta without other risk factors should not routinely be prescribed aspirin therapy as the benefits do not clearly outweigh the bleeding risks.

Evidence-Based Recommendation Analysis

Primary vs. Secondary Prevention Context

The key distinction in this case is whether atherosclerosis of the aorta alone constitutes a situation requiring primary or secondary prevention:

• Secondary prevention (established cardiovascular disease): Aspirin 75-162 mg daily is strongly recommended for patients with established atherosclerotic cardiovascular disease 1
• Primary prevention (risk factors but no established disease): The evidence is less clear and benefits may not outweigh risks

Specific Evidence for Aortic Atherosclerosis

The 2022 ACC/AHA guideline for aortic disease specifically addresses this scenario:

• For patients with abdominal aortic aneurysm (AAA) with concomitant atheroma and/or penetrating aortic ulcer (PAU), low-dose aspirin may be considered (Class 2b, Level of Evidence C-LD) 1
• This is a weak recommendation (may be considered) rather than a strong one (should be given)
• The guideline notes that "clinical outcomes data are limited, and further study of the efficacy of antiplatelet therapy in AAA is warranted" 1

Risk-Benefit Assessment

When considering aspirin for primary prevention:

1. Bleeding Risk:

   • Aspirin increases risk of gastrointestinal bleeding
   • The excess risk may be as high as 5 per 1,000 per year in real-world settings 1

2. Cardiovascular Benefit:

   • For isolated aortic atherosclerosis without other risk factors, the benefit is uncertain
   • The 2018 ADA guidelines note that "in adults with ASCVD risk >1% per year, the number of ASCVD events prevented will be similar to or greater than the number of events caused by aspirin" 1

Clinical Decision Algorithm

Step 1: Determine if this is truly primary prevention

• If the patient has had a previous cardiovascular event (MI, stroke, TIA) → Secondary prevention → Prescribe aspirin 75-162 mg daily
• If the patient has symptomatic peripheral arterial disease → Prescribe aspirin 75-162 mg daily 1
• If atherosclerosis of the aorta is the only finding → Primary prevention context → Proceed to Step 2

Step 2: Assess overall cardiovascular risk

• Calculate 10-year ASCVD risk
• If risk is high (>10%) and patient is between 40-70 years → Consider aspirin
• If risk is low (<10%) → Aspirin not recommended

Step 3: Assess bleeding risk

• Check for history of GI bleeding, peptic ulcer disease
• Consider age (>70 years increases bleeding risk)
• Consider concurrent medications (anticoagulants, NSAIDs)

Step 4: Make recommendation

• If isolated aortic atherosclerosis with no other risk factors and low ASCVD risk → Do not prescribe aspirin
• If aortic atherosclerosis with additional risk factors and high ASCVD risk → Consider low-dose aspirin (75-81 mg daily)

Common Pitfalls to Avoid

1. Overestimating benefit: Assuming all atherosclerosis requires antiplatelet therapy regardless of location or symptomatology

2. Underestimating bleeding risk: The risk of GI bleeding with aspirin is substantial and increases with age

3. Ignoring patient age: For patients over 70 years, the balance of aspirin for primary prevention appears to have greater risk than benefit 1

4. Using higher doses than necessary: If aspirin is indicated, 75-81 mg daily is the preferred dose as higher doses increase bleeding risk without providing additional cardiovascular protection 2

5. Assuming "aspirin resistance" requires higher doses: Despite some patients showing laboratory evidence of "aspirin resistance," this does not support routinely using higher doses 2, 3

In conclusion, for a patient with isolated atherosclerosis of the aorta and no other cardiovascular risk factors, the current evidence does not support routine aspirin therapy as the bleeding risks likely outweigh the uncertain cardiovascular benefits.