Should aspirin therapy be initiated in an adult over 50 with risk factors for atherosclerotic disease and Doppler ultrasound (USG) of the lower limbs showing atherosclerotic changes, indicating peripheral arterial disease (PAD)?

Should Aspirin Be Started for Atherosclerotic Changes on Lower Limb Doppler Ultrasound?

Yes, initiate aspirin 75-160 mg daily if the patient has symptomatic peripheral arterial disease (PAD), but the decision is more nuanced for asymptomatic atherosclerotic changes alone.

Symptomatic PAD: Clear Indication for Antiplatelet Therapy

If the Doppler ultrasound shows atherosclerotic changes AND the patient has symptoms (intermittent claudication, rest pain, prior revascularization, or amputation), aspirin therapy is strongly recommended. 1

• Aspirin 75-325 mg daily (typically 75-160 mg) reduces the risk of myocardial infarction, stroke, and vascular death in symptomatic PAD patients 1
• Clopidogrel 75 mg daily is an equally effective alternative and may be preferred based on the CAPRIE trial showing 24% relative risk reduction in cardiovascular events specifically in PAD patients 1, 2, 3
• The 2024 ESC Guidelines give this a Class I, Level A recommendation for symptomatic disease 1

Asymptomatic PAD: More Selective Approach

For asymptomatic atherosclerotic changes on Doppler (no claudication symptoms), the evidence is weaker and recommendations are more conditional.

When to Consider Aspirin in Asymptomatic PAD:

• If ABI ≤0.90: Antiplatelet therapy can be useful (Class IIa recommendation, Level C evidence) 1
• If diabetes is present with asymptomatic PAD: Aspirin 75-100 mg daily for primary prevention may be considered 1
• The 2024 ESC Guidelines explicitly state: "It is not recommended to systematically treat patients with asymptomatic PAD without any sign of clinically relevant atherosclerotic cardiovascular disease with antiplatelet drugs" 1

When NOT to Start Aspirin:

• If ABI is borderline (0.91-0.99): The usefulness of antiplatelet therapy is not well established (Class IIb, Level A) 1
• If truly asymptomatic without diabetes or other high-risk features: Recent trials (CLIPS, POPADAD) showed no benefit in reducing major adverse cardiovascular events or revascularization in asymptomatic patients 1

Critical Decision Algorithm

Follow this stepwise approach:

1. Confirm symptom status: Ask specifically about leg pain with walking that resolves with rest (claudication), rest pain, or history of lower extremity procedures 1

2. If symptomatic: Start aspirin 75-160 mg daily OR clopidogrel 75 mg daily immediately 1, 2, 3

3. If asymptomatic:

   • Measure ABI if not already done 1
   • If ABI ≤0.90 AND patient has diabetes: Consider aspirin 75-100 mg daily 1
   • If ABI ≤0.90 WITHOUT diabetes: Reasonable to consider aspirin, but evidence is weaker (Class IIa) 1
   • If ABI 0.91-0.99: Do not routinely start aspirin 1

4. Assess bleeding risk: Do not start aspirin if high bleeding risk (active peptic ulcer, recent major bleeding, severe thrombocytopenia) 1

Important Caveats and Pitfalls

Common mistakes to avoid:

• Don't assume all atherosclerotic changes warrant aspirin: The presence of atherosclerosis on imaging alone without symptoms or low ABI does not automatically indicate aspirin therapy 1
• Don't use dual antiplatelet therapy routinely: Aspirin plus clopidogrel increases bleeding risk without clear benefit in stable PAD and should only be considered in very high-risk patients post-revascularization 1
• Don't forget comprehensive cardiovascular risk reduction: All PAD patients (symptomatic or asymptomatic) need statin therapy, blood pressure control, smoking cessation, and diabetes management regardless of aspirin decision 1, 2, 3
• Don't use warfarin for PAD: Oral anticoagulation is not indicated for PAD alone and increases bleeding risk (Class III recommendation) 1

Emerging Evidence: Rivaroxaban Plus Aspirin

For symptomatic PAD patients at high ischemic risk and non-high bleeding risk, combination therapy with rivaroxaban 2.5 mg twice daily plus aspirin 100 mg daily should be considered (Class IIa, Level A) 1. This represents newer evidence showing benefit in reducing major adverse cardiovascular events and major adverse limb events, though with increased bleeding risk 4.