In a patient with incidentally identified abdominal aortic atheromatous plaque and no prior myocardial infarction, stroke, or symptomatic peripheral arterial disease, should routine low‑dose aspirin therapy be started?

Aspirin Therapy for Incidental Abdominal Aortic Atherosclerotic Plaque

Low-dose aspirin (75–100 mg daily) may be considered in patients with incidentally discovered abdominal aortic atheromatous plaque, but only if the plaque is severe or complex (≥4 mm thickness, mobile, or ulcerated components) and the patient has no contraindications or high bleeding risk. 1, 2

Risk Stratification Determines Treatment

The decision to initiate aspirin hinges on plaque characteristics:

• Non-severe/non-complex plaques (atheroma <4 mm, no mobile or ulcerated components) do not require antiplatelet therapy 2
• Severe/complex plaques (≥4 mm or mobile/ulcerated features) warrant consideration of single antiplatelet therapy after individualized bleeding risk assessment 1, 2

The 2022 ACC/AHA guidelines assign a Class 2b recommendation (Level C-LD) for low-dose aspirin in patients with abdominal aortic aneurysm (AAA) with concomitant atheroma, acknowledging that clinical outcomes data are limited and further study is warranted. 1

Evidence Base and Rationale

Cardiovascular risk reduction, not aortic-specific benefit, drives the recommendation:

• Atherosclerotic AAA carries >20% risk of cardiovascular events within 10 years and is considered a coronary artery disease equivalent 1
• Aspirin at 75–162 mg daily reduces stroke, myocardial infarction, and vascular death in patients with noncoronary atherosclerosis 1
• Incidentally detected abdominal aortic atherosclerosis is highly associated with significant coronary stenosis, particularly when stenosis ≥25% is present 3

Aortic-specific data show conflicting results:

• Small cohort studies suggest aspirin may reduce AAA growth rate at diameters 4.0–4.9 cm 1
• However, Danish registry data (4,010 patients) showed increased case-fatality in ruptured AAA among aspirin users (66% vs 57%; adjusted mortality ratio 1.16), though no increased rupture risk 1

Contraindications and Cautions

Do not initiate aspirin if:

• Active gastrointestinal hemorrhage or known aspirin allergy 1
• High bleeding risk outweighs cardiovascular benefit 1, 2
• Patient has asymptomatic PAD without diabetes or other high-risk features 1

Dual antiplatelet therapy is not recommended for asymptomatic aortic atherosclerosis because it increases bleeding risk without additional antithrombotic benefit. 2, 4

Anticoagulation is not indicated for asymptomatic aortic plaques and may theoretically increase risk of plaque hemorrhage leading to atheroemboli syndrome. 1, 2, 4

Comprehensive Management Beyond Aspirin

Statin therapy is more strongly recommended than aspirin:

• Initiate high-intensity statin targeting LDL-C <1.4 mmol/L (<55 mg/dL) in patients with severe/complex plaques ≥4 mm 2, 4
• Statins slow plaque progression and stabilize vulnerable plaques through lipid-lowering and anti-inflammatory mechanisms 1, 2

Mandatory lifestyle modifications:

• Smoking cessation is the single most important modifiable risk factor 1, 2
• Blood pressure control to <140/90 mmHg 2
• Mediterranean-style diet and regular aerobic exercise 2

Surveillance imaging:

• Duplex ultrasound every 3 years for mild atherosclerotic changes without aneurysmal dilation 2
• CT or MRI when ultrasound is insufficient 2
• Serial imaging detects plaque progression (≥5 mm/year or ≥1 grade increase), which predicts higher vascular event rates and prompts therapy escalation 2

Clinical Algorithm

1. Characterize the plaque on imaging: measure thickness, assess for mobile/ulcerated components
2. If plaque <4 mm and non-complex: Do not start aspirin; focus on statin therapy and risk factor modification 2
3. If plaque ≥4 mm or complex features present:
   • Assess bleeding risk (history of GI bleeding, concurrent anticoagulation, thrombocytopenia)
   • If low-to-moderate bleeding risk: Consider aspirin 75–100 mg daily 1, 2
   • If high bleeding risk: Defer aspirin, optimize statin and lifestyle measures 2, 4
4. Initiate high-intensity statin regardless of aspirin decision 2, 4
5. Arrange surveillance imaging at appropriate intervals 2

Common Pitfalls

• Overuse of aspirin in non-severe plaques: Aspirin carries bleeding risk without proven aortic-specific benefit in plaques <4 mm 2
• Neglecting statin therapy: Statins have stronger evidence for plaque stabilization than aspirin 1, 2
• Assuming aspirin prevents aneurysm rupture: Registry data suggest aspirin may worsen outcomes if rupture occurs 1
• Using dual antiplatelet therapy or anticoagulation: These increase bleeding without benefit in asymptomatic aortic disease 2, 4
• Failing to screen for coronary disease: Abdominal aortic atherosclerosis strongly predicts coronary stenosis; consider coronary evaluation 3