In a 72‑year‑old woman with right‑arm blood pressure 128/84 mm Hg and left‑arm blood pressure 143/97 mm Hg, how should the inter‑arm pressure discrepancy be evaluated and managed?

Management of Inter-Arm Blood Pressure Discrepancy

Use the left arm blood pressure of 143/97 mm Hg for all future blood pressure measurements and clinical decision-making in this patient, as current guidelines uniformly recommend using the arm with the higher reading for subsequent monitoring and hypertension management. 1

Immediate Action Required

• Document both readings and clearly note that the left arm consistently shows higher values (15 mm Hg systolic and 13 mm Hg diastolic difference). 1

• Repeat measurements on at least one additional visit to confirm the inter-arm difference is consistent, as ACC/AHA guidelines require averaging ≥2 readings obtained on ≥2 occasions to establish the patient's true blood pressure level. 1

• Designate the left arm as the standard measurement site for all future visits, documenting this clearly in the medical record. 1

Clinical Significance of This Discrepancy

The 15 mm Hg systolic difference in this patient exceeds the clinically significant threshold:

• Systolic differences >10 mm Hg occur in approximately 20% of the general population and warrant further evaluation. 2, 3

• Differences >15-20 mm Hg suggest possible subclavian or innominate artery stenosis, particularly in patients with peripheral arterial disease risk factors. 1

• At age 72, this patient should be evaluated for atherosclerotic vascular disease given the substantial inter-arm difference. 1

Evaluation Strategy

Assess for peripheral arterial disease through:

• Vascular examination: Palpate bilateral brachial, radial, and ulnar pulses; auscultate for subclavian bruits. 1

• Consider ankle-brachial index (ABI) testing if pulses are diminished or if other cardiovascular risk factors are present (diabetes, smoking history, hyperlipidemia). 1

• No immediate imaging is required unless the patient has symptoms of arm claudication, vertebrobasilar insufficiency, or other signs of subclavian steal syndrome. 1

Hypertension Classification Using Left Arm Values

Based on the left arm reading of 143/97 mm Hg:

• This represents Stage 2 hypertension by ACC/AHA 2017 criteria (≥140/90 mm Hg). 1

• Immediate pharmacological treatment is indicated along with lifestyle interventions, as Stage 2 hypertension requires prompt drug therapy initiation. 1

• Target blood pressure should be <130/80 mm Hg for most adults, individualized based on age and frailty status in elderly patients. 1

Common Pitfalls to Avoid

• Do not average the two arms – this is incorrect and will underestimate the true blood pressure. Always use the higher arm. 1

• Do not dismiss the inter-arm difference as measurement error without confirmation on repeat visits. 2, 3

• Do not use sequential measurements when assessing inter-arm differences in the future, as this overestimates the discrepancy; simultaneous measurements with validated devices are preferred. 3

• Ensure proper technique on repeat measurements: patient seated with back supported for >5 minutes, feet flat, arm at heart level, appropriate cuff size, no talking during measurement. 1

Follow-Up Monitoring

• Confirm readings at 1-2 additional office visits within 2-3 months to establish the diagnosis definitively. 1

• Consider home blood pressure monitoring to confirm office readings, using the left arm exclusively, with target <135/85 mm Hg. 1

• Reassess inter-arm difference periodically (e.g., annually) as consistency of inter-arm differences can vary, particularly in elderly patients. 4