When is testing for renal artery stenosis recommended?

Testing for Renal Artery Stenosis

Testing for renal artery stenosis should be pursued when patients present with specific high-risk clinical features that suggest renovascular disease, not as routine screening in all hypertensive patients. 1

Clinical Indications for Testing

Testing is recommended when the following high-risk features are present 1:

• Rapidly progressive, treatment-resistant arterial hypertension (requiring >3 antihypertensive medications with inadequate control) 1
• Rapidly declining renal function, particularly when temporally associated with initiation of ACE inhibitors or ARBs 1
• Flash pulmonary edema (recurrent episodes of acute pulmonary edema with relatively preserved left ventricular function) 1, 2
• Renal artery stenosis in a solitary functioning kidney 1
• Resistant hypertension (defined as uncontrolled BP despite optimal medical therapy) 1
• Early-onset hypertension or stroke at a young age with family history 1

Additional clinical scenarios warranting evaluation include 2, 3:

• Unexplained azotemia or renal insufficiency
• Abdominal bruit on physical examination (particularly if lateralizing) 3
• Unexplained hypokalemia in a hypertensive patient 1
• Cardiac destabilization syndromes (recurrent heart failure episodes) 2

Diagnostic Algorithm

First-Line Testing

Duplex ultrasound (DUS) is the recommended first-line imaging modality (Class I, Level B recommendation) 1, 4:

• Peak systolic velocity (PSV) ≥200 cm/s indicates >50% stenosis with sensitivity of 73-91% and specificity of 75-96% 4
• Renal-aortic ratio (RAR) >3.5 indicates ≥60% stenosis and improves specificity when combined with PSV 4
• Side-to-side difference of intrarenal resistance index ≥0.5 provides additional diagnostic information 1

Second-Line Testing

When DUS is inconclusive or suggests hemodynamically significant stenosis, MRA or CTA are recommended (Class I, Level B recommendation) 1:

• Gadolinium-enhanced three-dimensional MRA and CTA perform significantly better than other non-invasive modalities 5
• These modalities are preferred when DUS quality is limited by body habitus, bowel gas, or operator experience 5

Confirmatory Testing

Catheter-based angiography with physiologic measurements should be considered when 1:

• Non-invasive imaging confirms >70% stenosis AND high-risk clinical features are present 1
• Stenosis is 50-70% and hemodynamic significance needs confirmation 1
• Physiologic criteria for hemodynamically significant stenosis include:
  • Resting mean pressure gradient >10 mmHg 1
  • Systolic hyperemic pressure gradient >20 mmHg 1
  • Renal Pd/Pa ≤0.9 (or 0.8) 1

Critical Assessment Before Intervention

Before considering revascularization, kidney viability must be assessed (Class I, Level B recommendation) 1:

Signs of Viable Kidney (Favorable for Intervention) 1:

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

Signs of Non-Viable Kidney (Unfavorable for Intervention) 1:

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

Common Pitfalls to Avoid

Do not screen asymptomatic patients or those with well-controlled hypertension, as routine revascularization of unilateral atherosclerotic RAS is not recommended (Class III, Level A) 1. The 2024 ESC guidelines explicitly state that medical therapy is first-line treatment for atherosclerotic RAS 1, and revascularization should only be considered after optimal medical therapy has been established in patients with high-risk features and viable kidneys 1.

Avoid relying solely on anatomic stenosis severity—hemodynamic significance and kidney viability are equally important for determining who benefits from intervention 1. Multiple randomized trials have shown no benefit of routine revascularization for unilateral atherosclerotic RAS without high-risk features 1.

Special consideration for fibromuscular dysplasia: These patients warrant more aggressive evaluation and consideration for revascularization with primary balloon angioplasty, as they typically have better outcomes than atherosclerotic disease (Class IIa, Level B) 1.