What is the workup for renal artery stenosis (RAS)?

From the Guidelines

The diagnostic workup for renal artery stenosis should begin with non-invasive imaging studies, starting with a duplex ultrasound of the renal arteries, as recommended by the 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases 1. The workup should be tailored based on clinical presentation, including resistant hypertension, unexplained kidney dysfunction, flash pulmonary edema, or asymmetric kidney sizes on imaging.

• Non-invasive imaging studies, such as duplex ultrasound, CT angiography (CTA), or MR angiography (MRA) of the renal arteries, can detect abnormal blood flow patterns and velocity, and provide detailed anatomical visualization of stenotic lesions.
• Laboratory tests, including serum creatinine, estimated glomerular filtration rate (eGFR), and urinalysis, should be performed to assess baseline kidney function.
• Consider captopril renal scintigraphy in select cases to help determine the functional significance of stenosis.
• For definitive diagnosis, especially when revascularization is being considered, conventional catheter angiography remains the gold standard, allowing for pressure gradient measurements across the stenosis, as noted in the ACC/AHA 2005 practice guidelines for the management of patients with peripheral arterial disease 1.
• The workup should prioritize the detection of hemodynamically significant renal artery stenosis, which can be defined as a stenosis with a peak translesional gradient of greater than or equal to 20 mm Hg or a mean gradient greater than or equal to 10 mm Hg, as described in the ACC/AHA 2005 practice guidelines 1.
• Medical treatment options, including ACE inhibitors or ARBs, can be effective in managing hypertension associated with renal artery stenosis, and may confer a long-term mortality benefit, as noted in the 2018 scientific statement from the American Heart Association on resistant hypertension 1.
• Revascularization, either through endovascular procedures such as stenting or surgical revascularization, may be considered in select patients with renal artery stenosis, particularly those with resistant hypertension, unexplained kidney dysfunction, or episodes of pulmonary edema, as recommended by the 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases 1.

From the Research

Diagnosis of Renal Artery Stenosis (RAS)

• Renal artery stenosis can be diagnosed using multiple modalities, including:
  • Doppler ultrasound
  • Computed tomography angiography
  • Magnetic resonance angiography
  • Selective angiogram 2
• The diagnosis of RAS is crucial in identifying patients who may benefit from revascularization or medical therapy.

Treatment Options for RAS

• Medical therapy for RAS is directed primarily toward blood pressure control and cardiovascular risk factor reduction 3
• Renal artery revascularization is an additional treatment option for RAS associated with:
  • Ischemic nephropathy
  • Severe, poorly controlled hypertension despite aggressive medical therapy 3
• Revascularization may be accomplished through:
  • Open surgical revascularization
  • Angioplasty and stenting 3, 4

Patient Selection for Revascularization

• Careful patient selection is required when considering revascularization to maximize the potential benefits 2, 4
• Patients with refractory hypertension or progressive renal failure may benefit from revascularization 2, 5
• The ability for revascularization to improve control of congestive heart failure or to prevent hard cardiovascular end points has not been tested in randomized clinical trials 5

Medical Therapy for RAS

• Antihypertensive medications such as renin-angiotensin-aldosterone system inhibitors, along with statins and aspirin, have significantly improved the medical treatment of atherosclerotic RAS 5
• Medical therapy may exert beneficial effects in patients with RAS, including a better renal outcome and a decrease of restenosis rate 6