Diagnostic Approach for Renal Artery Stenosis

Initial Screening Imaging

The European Society of Cardiology recommends duplex ultrasound (DUS) as the first-line imaging modality for diagnosing renal artery stenosis, followed by CT angiography (CTA) or MR angiography (MRA) if DUS is inconclusive or suggests stenosis 1
DUS should be performed first in any patient with suspected renal artery stenosis, measuring peak systolic velocity (PSV), renal-aortic ratio (RAR), resistance index, and kidney size 1
If DUS suggests stenosis (PSV >180-200 cm/sec, RAR >3.5) or provides inconclusive results, proceed to CTA or MRA for definitive anatomic assessment 1

A stenosis is considered hemodynamically significant when ≥70% diameter stenosis by visual estimation or intravascular ultrasound 2
A stenosis is also considered hemodynamically significant when 50-69% stenosis with post-stenotic dilatation and/or significant trans-stenotic pressure gradient 2
Invasive pressure measurements showing resting mean gradient >10 mmHg, systolic hyperemic gradient >20 mmHg, or renal Pd/Pa ≤0.9 indicate hemodynamic significance 1

Kidney viability must be assessed as non-viable kidneys will not benefit from revascularization 1, 2
Signs of viability include kidney size >8 cm, distinct cortex >0.5 cm with preserved corticomedullary differentiation, albumin-creatinine ratio <20 mg/mmol, and renal resistance index <0.8 1

High-risk features that may warrant consideration of revascularization include flash pulmonary edema, resistant hypertension, progressive renal failure, or recurrent heart failure 1, 2

The American Heart Association recommends medical therapy as the Class I (Level A) recommendation for atherosclerotic renal artery stenosis, which must be optimized before any consideration of revascularization 3, 4
Medical management should include a renin-angiotensin system (RAS) blocker, high-intensity statin, low-dose aspirin, and additional antihypertensive agents to achieve BP <130/80 mmHg 4, 1

Revascularization should be considered (Class IIa) only when both clinical and anatomic criteria are met 1, 2
Clinical criteria include optimal medical therapy has been established and failed, and presence of high-risk features 2
Anatomic criteria include unilateral stenosis >70% or bilateral stenosis >70% or stenosis in solitary kidney, and signs of kidney viability 1, 2

Follow-up with renal DUS is recommended after renal artery stenting, within 30 days, at 6 months, at 12 months, and annually thereafter 1, 2
Re-intervention may be considered for in-stent restenosis ≥60% detected by DUS, recurrent symptoms, or >20% increase in serum creatinine 1