Bilateral Renal Artery Stenosis in the Elderly: Atherosclerosis is the Cause
In elderly patients with hypertension, diabetes, and smoking history, atherosclerotic disease accounts for over 90% of bilateral renal artery stenosis cases. 1, 2
Primary Etiology
Atherosclerotic renal artery disease is the overwhelming cause of bilateral renal artery stenosis in older patients, particularly those over 55 years of age. 1, 3 The prevalence of atherosclerotic RAS increases dramatically with age, reaching 6.8% overall in patients over 65 years (9.1% in men, 5.5% in women). 1
Key Risk Factor Profile
The typical patient with atherosclerotic bilateral RAS presents with multiple vascular risk factors:
- Advanced age (typically >55 years, with prevalence increasing substantially after 65) 1
- Hypertension (especially resistant or accelerated hypertension) 1, 4
- Diabetes mellitus (prevalence of RAS reaches 33% in diabetic patients with hypertension) 2, 5
- Tobacco smoking 1, 3
- Coexistent atherosclerotic disease elsewhere (coronary artery disease, peripheral arterial disease) 1, 4
The disease typically involves the ostium and proximal third of the main renal artery along with perirenal aortic atherosclerosis. 1
Alternative Causes (Much Less Common in Elderly)
Fibromuscular dysplasia accounts for less than 10% of renal artery stenosis cases and predominantly affects younger patients, particularly women under 50 years of age. 1, 6 This etiology is essentially irrelevant in the elderly population described in your question.
Other rare causes in elderly patients include:
- Takayasu arteritis (uncommon) 1
- Radiation fibrosis (history-dependent) 1
- Renal artery dissection (acute presentation) 1
Clinical Presentation Clues Supporting Atherosclerotic Bilateral RAS
Your patient's presentation likely includes several characteristic features:
- Resistant hypertension (uncontrolled on ≥3 medications including a diuretic) 1
- Accelerated or suddenly worsening hypertension in a previously controlled patient 1, 7
- Flash pulmonary edema with preserved systolic function (suggests bilateral disease with volume overload) 1, 7, 2
- Acute kidney injury when starting ACE inhibitors or ARBs (bilateral disease prevents compensatory mechanisms) 1, 7, 8
- Progressive azotemia with unexplained renal failure 1, 2
- Abdominal bruit on physical examination 1, 3
Diagnostic Confirmation
When bilateral atherosclerotic RAS is suspected based on the clinical profile:
- Duplex ultrasound serves as first-line screening, assessing peak systolic velocity (renal-aortic ratio >3.5 indicates ≥60% stenosis with 84-91% sensitivity and 95-97% specificity) 1, 7
- CT angiography or MR angiography provides anatomic confirmation with high accuracy (CTA: 64-100% sensitivity, 92-98% specificity; MRA: 88% sensitivity, 100% specificity) 1
- Laboratory findings include elevated creatinine, hypokalemia (especially with thiazide diuretics), and activated renin-angiotensin-aldosterone system 1, 7
Common Pitfall to Avoid
Do not assume fibromuscular dysplasia in any elderly patient with bilateral RAS, even if the presentation seems atypical. 9 While FMD is the classic cause in young patients, atherosclerosis dominates in the elderly population regardless of presentation. A 34-year-old patient with bilateral RAS might have atherosclerosis rather than FMD 9, but in your elderly patient with diabetes, hypertension, and smoking, atherosclerosis is virtually certain.
The presence of triple-vessel coronary artery disease further predicts significant atherosclerotic RAS in this population. 4