What is the management of fibromuscular dysplasia (FMD)?

Management of Fibromuscular Dysplasia (FMD)

Percutaneous transluminal renal angioplasty without stenting is the treatment of choice for fibromuscular dysplasia affecting the renal arteries, particularly when hypertension is present. 1

Understanding Fibromuscular Dysplasia

Fibromuscular dysplasia is a nonatherosclerotic, non-inflammatory vascular disease that primarily affects medium-sized arteries, with the renal and carotid arteries being most commonly involved. Key characteristics include:

• Most commonly affects women between 25-50 years of age, though it can occur in both genders at any age 1, 2
• Typically involves the middle and distal two-thirds of the main renal artery and may extend to branches, unlike atherosclerosis which affects the ostial and proximal segments 1
• Presents with a characteristic "string of beads" appearance in 80% of cases (medial fibroplasia subtype) 1, 2
• Should be considered a systemic arterial disease as subclinical lesions may be present at multiple arterial sites 2, 3

Diagnostic Approach

Diagnosis of FMD requires appropriate imaging studies:

• Duplex ultrasonography is recommended as an initial screening test (Class I recommendation) 1
• Computed tomographic angiography (in patients with normal renal function) and magnetic resonance angiography are recommended screening tests (Class I recommendation) 1
• Catheter angiography remains the gold standard and should be performed when clinical suspicion is high and noninvasive tests are inconclusive 1, 2
• Captopril renal scintigraphy, selective renal vein renin measurements, and plasma renin activity are not recommended as screening tests (Class III recommendation) 1

Treatment Approach

Medical Management

• All patients with FMD should receive appropriate medical therapy to reduce blood pressure initially 1
• When percutaneous intervention is not feasible, RAS blockers (ACEIs/ARBs) are the drugs of choice but require careful monitoring of renal function 1
• Antiplatelet therapy is recommended for asymptomatic individuals with FMD 4

Interventional Management

• Percutaneous transluminal renal angioplasty (PTRA) without stenting is the first-line revascularization technique for symptomatic renal FMD (Class IIa recommendation) 1
• Stenting should be considered only in the management of dissection or balloon angioplasty failure 1
• PTRA has shown high technical success rates (nearly 100%) with good long-term outcomes 5
• Long-term clinical benefit (improved hypertension control) is maintained in approximately 73% of patients at 5 years 5

Surgical Management

• Open surgical revascularization should be reserved for:
  • Cases with complex aneurysms
  • Complex lesions involving arterial bifurcation or branches
  • Failed endovascular therapy 1
• Surgical options include aortorenal bypass or nonanatomic bypass depending on patient age and aortic status 1

Special Considerations

• FMD is now recognized as a systemic disease affecting multiple vascular beds, requiring evaluation of other arterial territories, particularly carotid and vertebral arteries 1, 2
• Patients with FMD may develop complications including:
  • Arterial dissection
  • Aneurysm formation
  • Stroke (when cervicocranial arteries are involved) 2, 3
• Predictors of long-term clinical benefit after intervention include:
  • Duration of hypertension <8 years
  • Normal renal function (creatinine <1.5 mg/dL)
  • Adequate ipsilateral kidney size (>9 cm)
  • Normal contralateral kidney function 5

Follow-up Recommendations

• Regular blood pressure monitoring is essential following intervention
• Imaging surveillance is recommended to detect restenosis, which occurs in approximately 28% of cases at 5 years 5
• Repeat intervention may be necessary for restenosis to maintain blood pressure control 5