What are the initial workup and management steps for a patient suspected of having peripheral artery disease (PAD)?

Peripheral Artery Disease: Diagnosis and Initial Management

Identify At-Risk Patients Requiring Evaluation

All patients aged ≥65 years should be screened for PAD with comprehensive history, vascular examination, and ankle-brachial index (ABI) testing. 1

Additional high-risk groups requiring evaluation include:

• Ages 50-64 years with atherosclerotic risk factors (diabetes, smoking history, hyperlipidemia, or hypertension) 1
• Ages <50 years with diabetes plus one additional atherosclerotic risk factor 1
• Any age with known atherosclerotic disease elsewhere (coronary, carotid, subclavian, renal, mesenteric stenosis, or abdominal aortic aneurysm) 1
• Any patient presenting with exertional leg symptoms, nonhealing wounds, or ischemic rest pain 1

Focused History: Specific Symptoms to Assess

Query for classic claudication characteristics (though only 10% present this way): 2

• Reproducible leg discomfort triggered by walking a specific distance 3
• Predictably relieved within 10 minutes of rest without position change 3
• Does not occur at rest 3

Also assess for atypical presentations: exertional leg fatigue, ischemic rest pain, nonhealing wounds, or functional walking impairment even without classic claudication. 1

Physical Examination: Specific Findings to Document

Measure blood pressure in both arms to identify the higher systolic pressure (required for accurate ABI calculation) and detect subclavian stenosis (>15-20 mmHg difference is abnormal). 1

Palpate all four lower extremity pulses bilaterally (femoral, popliteal, dorsalis pedis, posterior tibial) and grade as: 0=absent, 1=diminished, 2=normal, 3=bounding. 1, 3

Auscultate for femoral bruits and inspect legs/feet for nonhealing wounds, gangrene, elevation pallor, or dependent rubor. 1

Critical pitfall: Absence of dorsalis pedis pulse alone is less reliable than posterior tibial pulse absence, as dorsalis pedis can be congenitally absent in healthy individuals. 1 The presence of all four pedal pulses makes PAD unlikely. 3

Diagnostic Testing Algorithm

Step 1: Resting Ankle-Brachial Index (Primary Test)

The resting ABI is the initial and often only test needed to establish PAD diagnosis. 1, 4

Technique: Measure systolic pressures at brachial arteries and ankles (dorsalis pedis and posterior tibial) in supine position using Doppler. Calculate ABI by dividing the higher ankle pressure by the higher arm pressure for each leg. 1

Interpretation: 4, 3

• ABI ≤0.90: PAD confirmed—proceed to management
• ABI 0.91-0.99: Borderline—consider exercise ABI if symptomatic
• ABI 1.00-1.40: Normal—if symptomatic, proceed to exercise ABI
• ABI >1.40: Noncompressible arteries (common in diabetes/renal disease)—proceed to toe-brachial index

Step 2: Exercise Treadmill ABI (When Resting ABI Normal/Borderline)

Exercise ABI testing is essential when resting ABI is normal or borderline (0.91-1.40) but clinical suspicion remains high. 1, 4

A post-exercise ABI decrease >20% from baseline confirms PAD. 4, 3

This test also objectively quantifies functional limitation in confirmed PAD patients. 1

Step 3: Toe-Brachial Index (For Noncompressible Arteries)

Use TBI when ABI >1.40 or in patients with diabetes/chronic kidney disease who may have calcified, noncompressible vessels. 1, 4, 3

TBI <0.70 indicates PAD. 4, 3

TBI is also useful for assessing perfusion in suspected critical limb ischemia. 1

Step 4: Segmental Pressures and Waveforms (Optional Adjunct)

Segmental lower extremity pressures with Doppler or plethysmographic waveforms can localize anatomic disease segments (aortoiliac, femoropopliteal, infrapopliteal) when performed alongside ABI. 1

When to Obtain Anatomic Imaging

Do NOT obtain anatomic imaging (duplex ultrasound, CTA, MRA, angiography) for asymptomatic PAD or patients managed with medical therapy alone. 3

Reserve anatomic imaging exclusively for highly symptomatic patients being considered for revascularization: 1

• First-line: Duplex ultrasound to diagnose anatomic location and stenosis severity 1, 3
• Alternatives: MRA with gadolinium or CTA 3
• Invasive angiography: Only when endovascular or surgical intervention is planned 1

Special Considerations for Critical Limb Ischemia

For patients with nonhealing wounds or suspected critical limb ischemia, assess critical perfusion parameters: 4

• Ankle pressure <50 mmHg
• Toe pressure <30 mmHg
• Transcutaneous oxygen pressure (TcPO₂) <30 mmHg

Apply the Wound, Ischemia, and foot Infection (WIfI) classification to estimate amputation risk. 4

Initial Management Framework

Once PAD is confirmed, initiate guideline-directed medical therapy focused on reducing cardiovascular events and improving symptoms: 2

Antiplatelet therapy: Clopidogrel preferred over aspirin 2

High-intensity statin: Target LDL <70 mg/dL 5

Blood pressure control: ACE inhibitors preferred 6, 5

Antidiabetic agents: GLP-1 receptor agonists and SGLT-2 inhibitors when applicable 2

Structured exercise therapy: Supervised programs improve walking distance 2, 6

Smoking cessation: Physician counseling, nicotine replacement, or bupropion 6

Cilostazol: Improves exercise time and claudication symptoms 2, 6, 5

Critical Pitfalls to Avoid

Never rely solely on classic claudication symptoms—90% of PAD patients present atypically. 2

Never skip bilateral arm blood pressure measurement—this leads to inaccurate ABI calculations and missed subclavian stenosis. 4, 3

Never accept normal resting ABI as excluding PAD when clinical suspicion is high—proceed to exercise ABI testing. 4, 3

Never use ABI alone in diabetic or chronic kidney disease patients—noncompressible arteries require TBI for accurate diagnosis. 4, 3

Never order anatomic imaging unless revascularization is being actively considered—this exposes patients to unnecessary procedural risk and cost. 3