What are the diagnostic tests and management options for a patient with suspected intermittent claudication and potential peripheral arterial disease (PAD)?

Diagnostic Testing for Intermittent Claudication

For patients with suspected intermittent claudication, obtain a resting ankle-brachial index (ABI) immediately as the initial diagnostic test—this simple, noninvasive measurement confirms peripheral artery disease (PAD) when ≤0.90 and guides all subsequent management decisions. 1, 2

Clinical Assessment Before Testing

History Elements to Elicit

• Classic claudication triad: reproducible leg discomfort triggered by walking a predictable distance, relieved within 10 minutes of rest without position change, and absent at rest 2
• Exertional leg symptoms including cramping, aching, or fatigue in calf, thigh, or buttock muscles 1
• Ischemic rest pain or nonhealing wounds suggesting critical limb ischemia 1
• Most PAD patients do not have classic claudication—they present with atypical leg symptoms or are asymptomatic, yet still have functional impairment 1

Physical Examination Findings

• Palpate and grade all four lower extremity pulses bilaterally (femoral, popliteal, dorsalis pedis, posterior tibial) using the 0-3 scale: 0=absent, 1=diminished, 2=normal, 3=bounding 1, 2
• Auscultate for femoral bruits 1
• Inspect legs and feet for hair loss, muscle atrophy, nonhealing wounds, or gangrene 1, 3
• Perform Buerger's test: elevation pallor after 2 minutes followed by dusky red flush upon dangling indicates severe PAD 3
• Measure blood pressure in both arms—a difference >15-20 mmHg suggests subclavian artery stenosis and affects ABI accuracy 1, 2

Diagnostic Testing Algorithm

Step 1: Resting ABI (Initial Test for All Suspected Cases)

Obtain resting ABI with or without segmental pressures and waveforms when history or physical examination suggests PAD. 1, 2

Interpretation framework: 1, 2

• ABI ≤0.90: Abnormal—PAD confirmed, proceed to management
• ABI 0.91-0.99: Borderline—consider exercise testing if symptomatic
• ABI 1.00-1.40: Normal—if symptomatic, proceed to exercise testing
• ABI >1.40: Noncompressible arteries (calcified vessels)—proceed to toe-brachial index

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

Perform exercise treadmill ABI testing for patients with exertional non-joint-related leg symptoms when resting ABI is >0.90 and ≤1.40. 1, 2 This unmasks PAD that manifests only with exertion—a post-exercise ABI decrease >20% from baseline confirms the diagnosis. 2

Exercise testing also objectively quantifies functional status in patients with confirmed PAD and abnormal resting ABI (≤0.90). 1, 2

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

Measure TBI when ABI >1.40 to diagnose PAD in patients with calcified, noncompressible arteries—common in diabetes and chronic kidney disease. 1, 2 A TBI <0.70 indicates PAD. 2

TBI is also useful for evaluating local perfusion in patients with nonhealing wounds or gangrene, even when resting ABI appears normal or borderline. 1

Step 4: Anatomic Imaging (Only When Revascularization Considered)

Do not obtain anatomic imaging for asymptomatic PAD or patients managed with medical therapy alone—this is a Class III (Harm) recommendation. 1, 2

For symptomatic patients being considered for revascularization: 1, 2

• First-line: Duplex ultrasound to diagnose anatomic location and stenosis severity
• Alternatives: MRA with gadolinium or CTA
• Invasive angiography: Reasonable for lifestyle-limiting claudication inadequate to guideline-directed medical therapy, or useful for critical limb ischemia when revascularization considered 1

Critical Pitfalls to Avoid

Do not rely solely on classic claudication symptoms—the majority of PAD patients have atypical or no symptoms yet still experience functional impairment. 1, 2

Do not skip bilateral arm blood pressure measurement—this identifies the arm with highest systolic pressure (required for accurate ABI calculation) and detects subclavian stenosis. 1, 2

Do not accept normal resting ABI as excluding PAD when clinical suspicion is high—proceed to exercise treadmill ABI testing to unmask exertional disease. 1, 2

Do not use ABI alone in diabetic or chronic kidney disease patients—noncompressible arteries (ABI >1.40) require TBI for accurate diagnosis. 1, 2

Do not order anatomic imaging unless revascularization is being actively considered—this exposes patients to unnecessary procedural risk and cost without changing management. 1, 2

Management After Diagnosis Confirmation

Once PAD is confirmed with ABI ≤0.90, initiate guideline-directed medical therapy immediately to prevent major adverse cardiovascular events and limb amputation: 2

• Antiplatelet therapy (aspirin or clopidogrel)
• High-intensity statin therapy
• Blood pressure control with ACE inhibitors or ARBs
• Smoking cessation
• Diabetes management

For symptom-specific claudication improvement, cilostazol 100 mg twice daily is the only FDA-approved pharmacological agent, demonstrating 28-100% improvement in maximal walking distance across eight clinical trials. 4, 5 Cilostazol is significantly more effective than pentoxifylline, which has shown indifferent results. 5

Supervised exercise programs provide maximum benefit for claudication improvement—home-based programs are an alternative when supervised programs are unavailable. 6