In an asymptomatic adult with carotid fibromuscular dysplasia and no prior cerebrovascular events, should I use dual antiplatelet therapy or just aspirin monotherapy?

Antiplatelet Therapy for Asymptomatic Carotid Fibromuscular Dysplasia

For asymptomatic carotid fibromuscular dysplasia, use aspirin monotherapy (75-100 mg daily), not dual antiplatelet therapy. 1

Primary Recommendation

• Single antiplatelet therapy with low-dose aspirin (75-100 mg daily) should be used for asymptomatic carotid FMD if the patient has low bleeding risk and additional cardiovascular risk factors (such as diabetes or other atherosclerotic disease). 1

• The 2024 ESC Guidelines specifically state that in patients with asymptomatic carotid stenosis >50%, long-term antiplatelet therapy (commonly low-dose aspirin) should be considered if bleeding risk is low (Class IIa, Level C). 1

• While these guidelines address atherosclerotic carotid stenosis, the same conservative antiplatelet approach applies to asymptomatic carotid FMD, as both conditions share similar thromboembolic risk profiles when asymptomatic. 2, 3

Why Not DAPT?

• Dual antiplatelet therapy provides no benefit over single antiplatelet therapy in asymptomatic carotid disease and increases bleeding risk. 1

• The ESC explicitly states that DAPT combining aspirin and clopidogrel "has no benefit over SAPT" in asymptomatic carotid stenosis. 1

• A retrospective study of 471 patients demonstrated that dual antiplatelet therapy (aspirin plus clopidogrel) was associated with increased all-cause mortality in asymptomatic carotid disease (47% vs 40%, P=0.05), particularly in patients older than 75 years (82% vs 56%, P=0.001). 4

• DAPT is reserved for symptomatic carotid disease (TIA or stroke), where it is recommended for the first 21 days, followed by single antiplatelet therapy long-term. 1

Clinical Context for FMD

• Fibromuscular dysplasia of the carotid arteries is a nonatherosclerotic, noninflammatory angiopathy that most commonly affects women aged 20-60 years. 3

• Many FMD cases are asymptomatic and discovered incidentally on imaging or by detection of a cervical bruit. 3

• Conservative medical therapy with antiplatelet agents is appropriate for asymptomatic carotid FMD, as the natural history suggests low stroke risk without intervention. 2, 3, 5

• In a series of 13 FMD patients followed for a mean of 47 months, only one patient (who was not operated on and received medical treatment) developed a transient ischemic attack, supporting the safety of conservative management. 5

When to Consider Aspirin

• Aspirin should be considered if the patient has additional cardiovascular risk factors (diabetes, hypertension, smoking, family history of atherosclerotic disease) that increase overall cardiovascular event risk. 1

• If the patient is truly asymptomatic with no other cardiovascular risk factors and low overall cardiovascular risk, observation without antiplatelet therapy may be reasonable, though this is controversial. 1

Critical Pitfalls to Avoid

• Do not use DAPT for asymptomatic carotid FMD – this increases bleeding risk without proven benefit and may increase mortality. 1, 4

• Do not confuse management of asymptomatic versus symptomatic carotid disease – symptomatic patients require DAPT for 21 days, then transition to single antiplatelet therapy. 1

• Monitor for development of symptoms (TIA, stroke, pulsatile tinnitus, cervical bruit) at follow-up visits, as this would change management to symptomatic protocols. 3