What is the recommended screening and management approach for a 65-year-old patient with a history of smoking, diabetes, high blood pressure, and high cholesterol who is at risk of peripheral artery disease (PAD) and may benefit from Ankle-Brachial Index (ABI) screening?

ABI Screening for High-Risk 65-Year-Old Patient

This 65-year-old patient with multiple cardiovascular risk factors (smoking, diabetes, hypertension, hyperlipidemia) should undergo resting ankle-brachial index (ABI) screening, as they meet established criteria for increased PAD risk and early detection can guide intensive cardiovascular risk reduction strategies. 1

Who Should Be Screened

Your patient clearly qualifies for ABI screening based on multiple guideline criteria:

• Age ≥65 years alone is sufficient to warrant screening according to ACC/AHA guidelines 1
• The combination of diabetes, smoking history, hypertension, and hyperlipidemia further strengthens the indication, as these four risk factors account for 75% of all PAD cases 1
• The 2024 ESC guidelines specifically recommend ABI screening for asymptomatic individuals aged ≥65 years, particularly women, and at younger ages when cardiovascular risk factors are present 1

Important caveat: The U.S. Preventive Services Task Force (USPSTF) found insufficient evidence to recommend routine screening in asymptomatic adults, citing lack of trials showing that screening improves patient outcomes 1. However, this conservative stance contrasts with ACC/AHA and ESC recommendations that emphasize the value of risk stratification and intensified preventive therapy 1.

How to Perform ABI Screening

The resting ABI is the required first-line diagnostic test with the following technique: 1, 2

• Obtain systolic blood pressures at both brachial arteries and both ankle arteries (dorsalis pedis and posterior tibial) using a handheld Doppler device 1, 2
• Calculate ABI for each leg by dividing the higher ankle pressure by the higher arm pressure 1, 2
• Also measure blood pressure in both arms initially, as an inter-arm difference >15-20 mmHg suggests subclavian stenosis 2

Interpreting ABI Results

Report results using these standardized thresholds: 1

• ABI ≤0.90: Diagnostic for PAD (80% sensitivity, 95% specificity) 1
• ABI 0.91-0.99: Borderline—consider repeat testing or exercise ABI if symptomatic 1
• ABI 1.00-1.40: Normal 1
• ABI >1.40: Noncompressible vessels (common in diabetes)—requires alternative testing 1

Critical consideration for this diabetic patient: ABI accuracy is lower in patients with diabetes due to medial arterial calcification causing falsely elevated readings 1. If ABI >1.40, proceed immediately to alternative testing such as toe-brachial index (TBI), with TBI <0.70 diagnostic for PAD 1.

What to Do Based on Results

If ABI ≤0.90 (PAD Confirmed)

Reclassify this patient to very high cardiovascular risk and initiate aggressive medical management: 1

• Antiplatelet therapy: Clopidogrel 75 mg daily is preferred over aspirin for symptomatic PAD 1, 3
• High-intensity statin therapy: Target LDL-C <55 mg/dL (1.4 mmol/L) with >50% reduction from baseline 1
• Blood pressure control: Target SBP 120-129 mmHg if tolerated 1
• Diabetes management: Prioritize SGLT2 inhibitors or GLP-1 receptor agonists with proven cardiovascular benefit 1
• Smoking cessation: This is the single most important modifiable intervention 1

If ABI 0.91-0.99 (Borderline)

• Consider exercise treadmill ABI testing if the patient develops exertional leg symptoms 1
• The usefulness of antiplatelet therapy in borderline ABI is uncertain (Class IIb evidence), but intensive risk factor modification is still warranted 1

If ABI 1.00-1.40 (Normal)

• Reassess every 2-3 years given the patient's high-risk profile 1
• Continue aggressive cardiovascular risk factor management regardless of ABI result 1

Common Pitfalls to Avoid

Do not skip screening in diabetic patients due to concerns about calcification—instead, plan for TBI measurement if ABI is noncompressible 1. The 2019 ESC diabetes guidelines specifically recommend ABI-based screening once at diabetes diagnosis, then after 10 years if initially normal (or after 5 years if other risk factors like smoking exist) 1.

Do not assume a normal ABI excludes significant cardiovascular risk—this patient requires intensive risk factor modification regardless of ABI results given their multiple risk factors 1. An abnormal ABI primarily serves to reclassify intermediate-risk patients to high-risk status, justifying more aggressive preventive therapy 1.

Do not order anatomic imaging (duplex ultrasound, CTA, MRA) for asymptomatic PAD—these studies are reserved for symptomatic patients being considered for revascularization 1.

Surveillance Strategy

If initial ABI is normal in this high-risk patient:

• Repeat ABI screening every 2-3 years 1
• Perform annual clinical assessment for new symptoms (claudication, rest pain, nonhealing wounds) and pulse examination 1
• In diabetic patients with normal resting ABI, consider TBI measurement to detect early disease 1

The yield of PAD screening averages 17% overall but ranges from 1-4% in lower-risk populations to 42% in high-risk groups 4. Given this patient's multiple risk factors, the pre-test probability of detecting PAD is substantially elevated, making screening particularly valuable 5.