What are the indications for renal artery intervention in patients with renal artery stenosis?

Indications for Renal Artery Intervention in Renal Artery Stenosis

Medical therapy with at least 3 antihypertensive medications (including a diuretic) at maximally tolerated doses is the mandatory first-line treatment for atherosclerotic renal artery stenosis, with intervention reserved only for specific high-risk clinical scenarios after medical therapy has failed. 1

Etiology-Specific Approach

Fibromuscular Dysplasia

• Percutaneous transluminal renal angioplasty (PTRA) WITHOUT stenting is the treatment of choice for fibromuscular dysplasia and should be considered as first-line revascularization (Class IIa recommendation). 1, 2
• Bailout stenting may be used only if angioplasty fails. 1
• This approach can restore renal perfusion pressure and effectively lower blood pressure. 1, 2

Atherosclerotic Renal Artery Stenosis

Anatomic Criteria Required (Must Meet ONE):

• ≥70% diameter stenosis by visual estimation or intravascular ultrasound 1, 2
• 50-69% diameter stenosis WITH hemodynamic confirmation:
  • Resting mean pressure gradient >10 mmHg, OR 1
  • Resting systolic translesional gradient ≥20 mmHg, OR 1
  • Hyperemic systolic gradient ≥20 mmHg, OR 1
  • Renal fractional flow reserve (Pd/Pa) ≤0.9 (or 0.8) 1
• 50-69% stenosis with post-stenotic dilatation 1, 2

Clinical Criteria Required (Must Meet ONE):

APPROPRIATE Indications (Class IIa):

• Flash pulmonary edema (sudden onset pulmonary edema) with severe RAS 1
• Accelerating decline in renal function with bilateral RAS or RAS in solitary functioning kidney 1
• Resistant hypertension (failure of ≥3 maximally tolerated antihypertensive medications, one being a diuretic) with unilateral >70% RAS and signs of kidney viability 1, 2
• Bilateral RAS (>70%) or RAS in solitary kidney with high-risk features and kidney viability 1, 2

MAY BE APPROPRIATE Indications (Class IIb):

• Recurrent heart failure despite maximal medical therapy with severe RAS 1
• Recurrent unstable angina despite maximal medical therapy with severe RAS 1
• Hypertension with unexplained unilaterally small kidney or chronic kidney disease with significant RAS 1
• Intolerance to 3-antihypertensive medication regimen with hemodynamically significant RAS 1
• Stable renal function with unilateral significant RAS (selected patients only) 1

RARELY APPROPRIATE (Class III):

• Newly diagnosed atherosclerotic RAS (should receive optimal medical therapy first) 1
• Well-controlled hypertension on current medications 1
• Poorly controlled hypertension on <3 antihypertensive medications 1
• Incidentally discovered RAS without symptoms 1
• Small (<7 cm pole to pole) nonviable kidneys 1
• Moderate RAS (50-69%) without hemodynamic confirmation 1

Assessment of Kidney Viability (Required Before Intervention)

Signs of Viability (Favors Intervention): 1

• Renal size >8 cm 1
• Distinct cortex >0.5 cm 1
• Albumin-creatinine ratio <20 mg/mmol 1
• Renal resistance index <0.8 1

Signs of Non-Viability (Intervention Rarely Appropriate): 1

• Renal size <7 cm 1
• Loss of corticomedullary differentiation 1
• Albumin-creatinine ratio >30 mg/mmol 1
• Renal resistance index >0.8 1

Technical Considerations

• Primary stenting is standard practice for atherosclerotic RAS (not for fibromuscular dysplasia). 1
• Intravascular ultrasound should be used to optimize stent sizing, as undersizing increases restenosis risk and oversizing risks vessel rupture. 1
• Translesional pressure gradient measurement is necessary for moderate stenoses (50-69%) since invasive angiography alone cannot distinguish hemodynamic significance. 1
• Open surgical revascularization should be considered when endovascular intervention is technically unfeasible or has failed. 1

Post-Intervention Surveillance

Mandatory follow-up schedule: 2

• Within 30 days 2
• At 6 months 2
• At 12 months 2
• Annually thereafter 2

Re-intervention may be considered for: 1

• In-stent restenosis ≥60% detected by duplex ultrasound 1
• Recurrent symptoms (diastolic BP >90 mmHg on >3 antihypertensive drugs) 1

• 20% increase in serum creatinine 1

Critical Pitfalls to Avoid

• Do not intervene without first establishing optimal medical therapy (3 antihypertensive medications at maximal tolerated doses, including a diuretic). 1, 2
• Do not use stenting for fibromuscular dysplasia as primary treatment; angioplasty alone is preferred. 1, 2
• Do not intervene on kidneys <7 cm or with other signs of non-viability, as outcomes are poor. 1
• Do not rely on visual angiographic estimation alone for moderate stenoses (50-69%); hemodynamic confirmation is required. 1
• Do not intervene on incidentally discovered RAS without clinical manifestations. 1