When do you treat renal artery stenosis in patients with uncontrolled hypertension, impaired renal function, or symptoms like flash pulmonary edema?

When to Treat Renal Artery Stenosis

Optimal medical therapy with at least 3 antihypertensive medications (including a diuretic) at maximally tolerated doses is the first-line treatment for atherosclerotic renal artery stenosis, and revascularization should only be considered when specific high-risk clinical scenarios persist despite this medical management. 1, 2

Initial Management: Medical Therapy First

All patients with newly diagnosed atherosclerotic renal artery stenosis should receive optimal medical therapy before any consideration of revascularization. 1, 2

• Medical therapy must include 3 antihypertensive medications at maximally tolerated doses, with one being a diuretic 1
• ACE inhibitors or ARBs are recommended for unilateral stenosis and confer long-term mortality benefit 1
• Patients intolerant of 3 medications at maximal doses may be considered for earlier intervention 1
• Routine revascularization for atherosclerotic disease is NOT recommended based on randomized trial data (CORAL trial) 1

Anatomic Criteria Required for Intervention

Both clinical AND anatomic criteria must be met before revascularization is appropriate. 1, 2

Anatomic thresholds include:

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

Clinical Indications for Revascularization

Class I (Appropriate) Indications:

Flash pulmonary edema with severe RAS is the strongest indication for revascularization 1, 2

Class IIa (May Be Appropriate) Indications:

• Resistant hypertension failing ≥3 maximally tolerated antihypertensive medications (including a diuretic) with severe RAS 1, 2
• Accelerating decline in renal function with bilateral RAS or RAS to a solitary functioning kidney 1, 2
• Recurrent unexplained congestive heart failure or recurrent unstable angina despite maximal medical therapy with severe RAS 1, 2
• Malignant or accelerated hypertension with severe RAS 1
• Hypertension with unexplained unilateral small kidney 1

Class III (Rarely Appropriate) Indications:

• Well-controlled hypertension with RAS 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 stenosis (50-69%) without hemodynamic confirmation 1

Special Consideration: Fibromuscular Dysplasia

Balloon angioplasty WITHOUT stenting is the treatment of choice for fibromuscular dysplasia-related renal artery stenosis with symptomatic renovascular hypertension. 1, 2

• FMD has better outcomes with revascularization than atherosclerotic disease 1
• Stenting should only be used as bailout for dissection or angioplasty failure 1, 2
• Major complication rates are lower with endovascular therapy (6.3%) versus open surgery (15.4%) 1

Assessment of Kidney Viability Before Intervention

Kidney viability must be assessed before considering revascularization, as intervention in nonviable kidneys is rarely appropriate. 1

Signs of viability:

• Kidney 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):

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

Post-Intervention Surveillance

After renal artery stenting, structured follow-up with duplex ultrasound is recommended. 1

• Initial follow-up at 1 month 1
• Subsequent follow-up at 6 months, 12 months, then annually 1
• Re-intervention may be considered for in-stent restenosis ≥60% with recurrent symptoms (diastolic BP >90 mmHg on >3 medications or >20% increase in serum creatinine) 1

Critical Pitfalls to Avoid

• Do not revascularize based on anatomic stenosis alone—clinical high-risk features must be present 1, 2
• Do not intervene on incidentally discovered stenosis without attempting optimal medical therapy first 1
• Do not use ACE inhibitors/ARBs in bilateral severe stenosis without close monitoring, though they may be considered if well-tolerated 1
• Do not revascularize small, nonviable kidneys (<7 cm)—outcomes are poor 1
• Do not assume all moderate stenoses (50-69%) are hemodynamically significant—require pressure gradient confirmation 1