How should I evaluate and manage a 73-year-old woman with chronic kidney disease and coronary artery disease who has a ≥15 mm Hg inter-arm blood pressure difference?

Evaluation and Management of Inter-Arm Blood Pressure Difference in a 73-Year-Old Woman with CKD and CAD

This patient requires immediate vascular imaging to rule out subclavian artery stenosis or other critical arterial obstruction, and all future blood pressure measurements must be taken from the arm with the higher reading to avoid undertreating her hypertension.

Immediate Diagnostic Evaluation

Confirm the Finding

• Repeat bilateral blood pressure measurements simultaneously or sequentially using proper technique to confirm the ≥15 mm Hg difference, as this threshold is definitively abnormal and strongly suggests underlying vascular pathology 1, 2
• Ensure both arms are positioned at heart level with back and arms fully supported, using appropriately sized cuffs for each arm based on circumference 1, 2
• Document which arm has the higher reading, as this will be used for all future measurements 1

Focused Vascular Examination

• Palpate bilateral brachial, radial, dorsalis pedis, and posterior tibial pulses and rate them as 0 (absent), 1 (diminished), 2 (normal), or 3 (bounding) 1
• Auscultate for bruits over the femoral arteries and supraclavicular/infraclavicular regions to detect subclavian or femoral artery stenosis 1, 2
• Assess for signs of peripheral artery disease including diminished pulses, pulse delays between arms, and inspection of legs and feet for ischemic changes 1, 2
• Inquire about symptoms of vertebral artery steal syndrome such as dizziness, vertigo, or syncope that worsens with arm use 2
• Look for arm claudication, coolness, or pallor in the limb with lower blood pressure 2

Diagnostic Imaging

First-Line Imaging

• Order duplex ultrasound of subclavian and axillary arteries as the initial noninvasive test to detect stenosis or occlusion 2
• Obtain CT angiography or MR angiography of the aortic arch and great vessels if ultrasound is equivocal or to better delineate the level and extent of obstruction 2

Additional Testing

• Calculate ankle-brachial index (ABI) using the higher of the right or left arm blood pressure as the denominator, as patients with confirmed peripheral artery disease are at substantially increased risk for subclavian artery stenosis 1, 2
• An ABI <0.9 confirms lower extremity peripheral artery disease and increases suspicion for concomitant upper extremity disease 1

Blood Pressure Management Implications

Measurement Protocol

• Use the arm with the higher systolic pressure for all subsequent blood pressure measurements and hypertension management to avoid underestimating blood pressure and undertreating hypertension 1, 2
• This is critical because using the lower-reading arm would lead to inadequate blood pressure control and increased cardiovascular risk 2

Blood Pressure Target

• Target blood pressure <130/80 mm Hg in this patient with CKD and CAD, as recommended by the 2017 ACC/AHA guidelines 1
• The SPRINT trial demonstrated that intensive blood pressure management (systolic <120 mm Hg) provided cardiovascular benefits in patients with CKD (eGFR 20-60 mL/min/1.73 m²), though the practical target is <130/80 mm Hg 1
• Given her age (73 years) and comorbidities, incremental blood pressure reduction with careful monitoring for orthostatic hypotension and electrolyte abnormalities is appropriate 1

Antihypertensive Medication Selection

• Continue or initiate an ACE inhibitor or ARB as first-line therapy, particularly if albuminuria ≥300 mg/day is present 1
• Add a thiazide-like diuretic or calcium channel blocker as second-line therapy to augment blood pressure control 1
• Monitor for serum creatinine increases up to 30% after starting ACE inhibitor/ARB, which reflects reduced intraglomerular pressure rather than true kidney injury 1
• Avoid combining ACE inhibitor with ARB due to demonstrated harms in large trials 1

Referral and Ongoing Management

Vascular Surgery Consultation

• Refer to vascular surgery or cardiology for evaluation of subclavian stenosis and consideration of revascularization 2
• Symptomatic patients with arm claudication or subclavian steal syndrome require revascularization via endovascular or surgical techniques 2
• Asymptomatic chronic subclavian stenosis may be managed conservatively with medical therapy if collateral circulation is adequate 2

Cardiac Evaluation

• Perform ECG and cardiac evaluation because patients with subclavian artery disease frequently have concomitant coronary artery disease 2, 3
• This is particularly important given her existing CAD diagnosis 3, 4

Critical Pitfalls to Avoid

• Do not dismiss the finding as measurement error without proper confirmation with repeat measurements using correct technique 2
• Do not use different cuff sizes or measurement techniques between arms, as this creates artificial differences 1, 2
• Do not fail to position both arms at heart level, as arm position errors can create artificial differences of 10 mm Hg or more 1, 2
• Do not overlook the need for urgent evaluation when differences exceed 15-20 mm Hg, as this strongly suggests vascular pathology requiring investigation 1, 2
• Do not measure blood pressure in the lower-reading arm for hypertension management, as this will lead to undertreatment 1, 2