What is the management approach for fibromuscular dysplasia (FMD) findings on the internal carotid artery (ICA)?

Management of Fibromuscular Dysplasia in the Internal Carotid Artery

For patients with FMD of the ICA, initiate antiplatelet therapy (aspirin 81-325 mg daily) regardless of symptoms, perform annual noninvasive imaging initially, and reserve revascularization exclusively for symptomatic patients who have experienced retinal or hemispheric ischemic events. 1

Antiplatelet Therapy

All patients with carotid FMD should receive antiplatelet therapy to prevent thromboembolism, even when completely asymptomatic. 1, 2

• Aspirin 81-325 mg daily is the recommended agent 1, 2
• This applies to both symptomatic and asymptomatic patients 1, 2
• The mechanism is prevention of platelet deposition on fibrous webs that can serve as a nidus for thrombus formation 1
• Common pitfall: Withholding antiplatelet therapy in asymptomatic patients is inappropriate—guidelines clearly support its use in all carotid FMD cases 2

Surveillance Imaging Strategy

Perform annual noninvasive imaging initially to detect disease progression, then reduce frequency once stability is confirmed. 1, 2

• Acceptable modalities include contrast-enhanced CTA, MRA, or catheter-based angiography 1, 2
• The classic "string of beads" appearance on angiography confirms medial fibroplasia, the most common subtype 1
• Annual imaging is reasonable initially, though the effect on outcomes remains unclear 1
• Once stability is documented, imaging intervals can be extended 1, 2

Blood Pressure Control and Lifestyle Modification

In patients with FMD and prior stroke/TIA, implement blood pressure control and lifestyle modifications alongside antiplatelet therapy. 1

• These measures are recommended for secondary prevention of ischemic events 1
• Blood pressure should be controlled to normal range to reduce arterial wall stress 1

Revascularization Decisions

Asymptomatic Patients

Revascularization is NOT recommended for asymptomatic FMD regardless of stenosis severity. 1, 2

• This is a Class III (No Benefit) recommendation 1
• Medical management with antiplatelet therapy is the appropriate strategy 1, 2
• Research data support this conservative approach, showing no benefit from prophylactic intervention 3

Symptomatic Patients

For patients with retinal or hemispheric cerebral ischemic symptoms (TIA, stroke, amaurosis fugax) attributable to FMD, carotid angioplasty with or without stenting is reasonable. 1, 2

• This applies specifically to symptoms ipsilateral to the FMD lesion 1, 2
• Intervention is particularly reasonable for recurrent ischemic events despite optimal medical management 1
• Both endovascular and surgical approaches have been successful, though comparative data are lacking 1
• Research series demonstrate excellent long-term results with stent grafting 4 and graduated endoluminal dilatation 5, 6

Special Considerations for FMD with Dissection

If FMD presents with carotid dissection but no intraluminal thrombus, antiplatelet therapy is reasonable for secondary prevention. 1

• For dissection with ischemic symptoms, either anticoagulation (heparin bridging to warfarin for 3-6 months) or antiplatelet therapy is reasonable 1
• Antiplatelet therapy may be substituted for anticoagulation 1
• If symptoms persist despite antithrombotic therapy, angioplasty and stenting may be considered 1

Clinical Context and Pathophysiology

FMD is a nonatherosclerotic, noninflammatory arterial disease that predominantly affects middle-aged women 1, 2

• Symptoms result from either reduced blood flow through stenotic segments or thromboembolism from platelet aggregation on fibrous webs 1, 2
• Potential manifestations include stroke, TIA, carotid dissection, Horner syndrome, cranial nerve palsies, and subarachnoid hemorrhage 1, 2
• The disease frequently involves the ICA bilaterally, typically 3-4 cm from the bifurcation 1
• Associated complications include arterial elongation, kinking, coiling, and aneurysmal dilation 1

Key Caveats

• The optimal antiplatelet drug and dosing regimen have not been definitively established through trials 1
• Comparative data between different revascularization methods (angioplasty alone versus stenting, endovascular versus surgical) are not available 1
• Research suggests that operated symptomatic patients have no recurrent symptoms, while some medically managed symptomatic patients do experience recurrence 5, 6, 3
• The natural history and pathophysiology of FMD remain incompletely understood 1