Should patients with asymptomatic carotid stenosis be treated with Aspirin (Acetylsalicylic Acid)?

Antiplatelet Therapy in Asymptomatic Carotid Stenosis

Long-term antiplatelet therapy (commonly low-dose aspirin) should be considered in patients with asymptomatic >50% carotid stenosis if bleeding risk is low. 1

Evidence-Based Recommendation

The 2024 European Society of Cardiology (ESC) guidelines provide the most recent and highest quality evidence on this topic, giving a Class IIa, Level C recommendation for long-term antiplatelet therapy in patients with asymptomatic carotid stenosis >50% 1. This recommendation acknowledges that while definitive evidence from randomized controlled trials is limited, antiplatelet therapy is reasonable in this population due to their elevated cardiovascular risk profile.

Rationale and Evidence Analysis

Limited Direct Evidence

The only randomized controlled trial specifically addressing antiplatelet therapy in asymptomatic carotid stenosis (the Asymptomatic Cervical Bruit Study) failed to show superiority of aspirin versus placebo in reducing TIA, stroke, MI, or death 1, 2. This study was underpowered with only 188 patients per arm.

Observational Data and Risk Profile

Despite limited direct evidence from RCTs:

• Observational studies show SAPT (mainly low-dose aspirin) is associated with reduced risk of major adverse cardiovascular events (MACE) 1
• Patients with asymptomatic carotid stenosis have approximately twice the risk of myocardial infarction compared to the general population 1
• The annual stroke risk in medically treated asymptomatic carotid stenosis is relatively low (0.93%) but the risk of cardiac events is significant (4.21%) 3

Dual Antiplatelet Therapy

• DAPT combining aspirin and clopidogrel has shown no benefit over SAPT in asymptomatic carotid stenosis 1
• The COMPASS trial reported a non-significant decrease in MACE with dual pathway therapy (aspirin plus low-dose rivaroxaban) compared to aspirin alone, but specific data on asymptomatic carotid stenosis were not reported 1

Clinical Application Algorithm

1. Identify patients with asymptomatic carotid stenosis >50% through appropriate imaging (typically duplex ultrasound)

2. Assess bleeding risk using validated tools:

   • Low bleeding risk: Consider antiplatelet therapy
   • High bleeding risk: Weigh risks vs. benefits carefully

3. Select appropriate antiplatelet agent:

   • First choice: Low-dose aspirin (75-100 mg daily) 1
   • Alternative: Clopidogrel 75 mg daily (particularly in aspirin-intolerant patients) 1

4. Consider higher risk subgroups who may derive greater benefit:

   • Diabetic patients 1
   • Patients with multiple cardiovascular risk factors
   • Patients with higher-grade stenosis (>70%)
   • Patients with high-risk plaque features (echolucent, large, or with intraplaque hemorrhage) 1

Important Caveats and Considerations

• Antiplatelet therapy should be part of comprehensive cardiovascular risk factor management including:

  • Blood pressure control
  • Lipid management
  • Smoking cessation
  • Diabetes management

• The benefit of antiplatelet therapy must be weighed against bleeding risk in each individual case

• Patients with asymptomatic carotid stenosis should be monitored for progression to symptomatic disease, which would warrant different management strategies

• The ongoing CREST-2 trial results are awaited to clarify whether intervention is beneficial in asymptomatic carotid stenosis compared with modern optimal medical therapy 1