Diagnosis & Treatment of Renal Artery Stenosis (RAS)
Diagnosis & Treatment of Renal Artery Stenosis (RAS)
Source (Hypertension News – Dec 2025)
Keynotes:
1. Types of Renal Artery Stenosis
• Atherosclerotic RAS (ARAS): majority of cases; driven by flow disturbances + intrarenal inflammation.
• Fibromuscular Dysplasia (FMD): increasingly recognized; kidney structure preserved, similar to essential hypertension.
2. When to Suspect RAS
Key clinical clues:
• Resistant or sudden-onset hypertension
• Ischemic nephropathy or unexplained decline in eGFR
• “Cardiac destabilization syndromes”: flash pulmonary edema, recurrent HF, ACS
• Abdominal bruit, unexplained hypokalemia
• Strongest predictors of significant RAS:
• Kidney length asymmetry ≥10%
• Peripheral / extra-renal atherosclerosis
• Newly developed hypertension
3. Diagnostic Imaging Modalities for RAS
A. Duplex Ultrasound (DUS)
• Pros: Noninvasive, no radiation, inexpensive
• Cons: Operator-dependent, limited in obese/abdominal gas
B. Computed Tomography Angiography (CTA)
• Pros: Excellent anatomical detail
• Cons: Uses iodinated contrast → may worsen kidney function in CKD; exposes to radiation
C. Magnetic Resonance Angiography (MRA)
• Pros: High-quality arterial images WITHOUT ionizing radiation
• Kidney Safety:
• Safe when using modern Group II gadolinium agents
• Avoid only in eGFR < 30 mL/min/1.73m² if Group I gadolinium is used (risk of NSF)
• Thus: MRA generally does NOT harm kidneys when proper agents are used
D. Digital Subtraction Angiography (DSA) — Gold Standard
• Pros: Most accurate; allows immediate intervention
• Cons: Invasive; uses iodinated contrast + radiation
Important Clarification
• All imaging shows anatomy only, not whether stenosis is hemodynamically or clinically significant.
• No biomarker reliably distinguishes true renovascular hypertension.
4. Treatment Options
• Medical therapy: first-line for most cases
• Percutaneous Transluminal Renal Angioplasty (PTRA ± stenting)
• Surgery: rarely used today
Evidence Summary from Trials (ASTRAL, CORAL, others):
• No major benefit of angioplasty vs. medical therapy in:
• Cardiovascular mortality
• CVD events
• Preserving kidney function
• Blood pressure reduction
• Small reduction in number of antihypertensive drugs (~0.4)
Limitations of trials: high heterogeneity, low representation of advanced disease.
5. Current Interventional Perspective
• Some recommend revascularization only when pressure-gradient testing suggests hemodynamic significance — but no evidence this improves outcomes.
• ACC/AHA/SCAI “Appropriate Use” Criteria support angioplasty in:
• Cardiac destabilization syndromes
• Rapidly worsening kidney function
• Stage IV CKD + resistant HTN with bilateral RAS
• RAS in a solitary functioning kidney
• Not recommended for incidental or newly discovered asymptomatic ARAS.
6. Management of Fibromuscular Dysplasia (FMD)
• Anti-atherosclerotic therapy not required (non-atherosclerotic disease).
• Angioplasty reasonable in patients <50 years with significant stenosis.
• No randomized trials exist.
7. Unilateral vs Bilateral RAS(JACC Cardiovasc Interv 2019 ACC/SCAI)
• Most likely to benefit from revascularization due to:
• Severe RAAS activation
• Sodium/water retention → volume overload
• Declining GFR
• Recurrent flash pulmonary edema / HF
• Hemodynamic instability
Selected unilateral high-grade RAS cases may also benefit, especially when:
• The affected kidney shows rapid decline
• Blood pressure becomes destabilized
• The patient has a solitary functioning kidney
Source: ACC/SCAI Appropriate Use Criteria (JACC Cardiovasc Interv 2019)
ARR Clarification
The aldosterone–renin ratio (ARR) is not useful in diagnosing renovascular hypertension because:
• Both renin and aldosterone rise proportionally in RAS
• Unlike primary aldosteronism, where aldosterone rises disproportionately
8. Overall Clinical Conclusion
• No single evidence-based algorithm exists for RAS management.
• Best practice today:
• Screen with CTA
• Confirm with DSA
• Decide on angioplasty individually, based on symptoms and kidney function
• Apply aggressive cardiovascular prevention (statins, antiplatelets) in ARAS
