What is the role of renal artery stents in treating renovascular disease?

Renal Artery Stents for Renovascular Disease

Medical therapy should be the first-line treatment for all patients with renovascular disease, with renal artery stenting reserved for specific high-risk clinical scenarios including flash pulmonary edema, resistant hypertension despite maximal medical therapy, rapidly declining renal function, or fibromuscular dysplasia. 1

Initial Management: Medical Therapy First

All patients with renovascular disease should receive intensive medical management before considering revascularization 1:

• Antihypertensive medications including thiazide diuretics, calcium channel blockers, and beta-blockers are recommended as first-line agents 1
• Statin therapy is essential given the high cardiovascular risk and evidence of improved survival and slower lesion progression 1
• Antiplatelet therapy (low-dose aspirin) should be part of standard medical management 1, 2
• ACE inhibitors or ARBs are effective for unilateral stenosis but require careful monitoring 1

Critical Caveat with RAS Blockers

ACE inhibitors and ARBs must be avoided or used with extreme caution in bilateral renal artery stenosis or stenosis of a solitary functioning kidney due to risk of acute renal failure 1. When used in unilateral disease, 10-20% of patients will develop an unacceptable rise in serum creatinine, particularly with volume depletion 1, 2. Close monitoring of renal function is mandatory 1.

When to Consider Renal Artery Stenting

Fibromuscular Dysplasia (FMD)

Percutaneous transluminal renal angioplasty (PTRA) WITHOUT stenting should be considered as first-line treatment for FMD (Class IIa recommendation) 1. This is the one scenario where intervention is preferred over prolonged medical management, as angioplasty alone can restore renal perfusion and lower blood pressure effectively 1. Stenting should only be added if angioplasty fails or dissection occurs 1.

Atherosclerotic Renal Artery Stenosis

Renal artery angioplasty WITH stenting may be considered (Class IIb recommendation) only in highly selected patients with hemodynamically significant atherosclerotic stenosis (≥70% or 50-69% with post-stenotic dilatation) who have 1:

• Recurrent flash pulmonary edema (Pickering syndrome) despite maximal medical therapy 1
• Resistant hypertension uncontrolled on maximal medical therapy 1
• Rapidly declining renal function with bilateral stenosis or unilateral stenosis in a solitary kidney 1
• Recurrent heart failure or unstable angina despite optimal medical management 1

Important Context on Atherosclerotic Disease

The 2024 ESC guidelines acknowledge that recent randomized trials (including CORAL) showed no benefit of stenting over medical therapy alone for most patients with atherosclerotic renal artery stenosis 1. However, the guidelines note these trials had significant limitations—they did not exclusively recruit patients with true hemodynamically significant renovascular hypertension 1. Post-hoc analysis of CORAL suggests potential mortality benefit in patients without proteinuria 1.

The key clinical concern is that overly conservative approaches may result in uncontrolled hypertension, recurrent flash pulmonary edema, and progression to end-stage renal disease in high-risk phenotypes 1.

Technical Considerations

When stenting is performed:

• Procedures should be performed in experienced centers due to high risk of restenosis (approximately 16-19% at 6-12 months) 1, 3, 4
• Stenting is superior to balloon angioplasty alone for atherosclerotic ostial lesions, with procedural success rates of 96-100% versus 63-77% for angioplasty alone 1, 4
• Larger post-stent minimal lumen diameter correlates with better late patency 1
• Procedure-related mortality is low (0.5-1%) but complications occur in approximately 13% of patients 1, 3

Outcomes and Monitoring

Blood Pressure Response

Stenting rarely cures hypertension (only 9-16% achieve cure defined as DBP ≤90 mmHg off medications) but can improve blood pressure control and reduce medication burden 1, 3, 4. The best predictor of effective blood pressure reduction after revascularization is a short duration of hypertension 1, 2.

Renal Function

Among patients with impaired baseline renal function undergoing stenting 3:

• 26% improve
• 48% stabilize
• 26% deteriorate

Patients with severe renal impairment (creatinine ≥400 μmol/L) have a 50% risk of requiring dialysis after stenting 3. However, in carefully selected patients with declining renal function, successful stenting can slow progression to end-stage renal disease 1, 5.

Algorithm for Decision-Making

1. All patients: Start intensive medical therapy (antihypertensives, statin, antiplatelet)
2. If FMD: Consider PTRA without stenting (Class IIa)
3. If atherosclerotic disease: Continue medical therapy unless patient develops:
   • Flash pulmonary edema → Consider stenting
   • Resistant hypertension on ≥3 drugs → Consider stenting
   • Rapid GFR decline with bilateral/solitary kidney stenosis → Consider stenting
4. Avoid stenting in patients without hemodynamically significant stenosis or those with severe baseline renal impairment (creatinine ≥400 μmol/L) unless life-threatening complications 1, 3