What is the evaluation and management of symptomatic Peripheral Artery Disease (PAD)?

Evaluation of Symptomatic Peripheral Artery Disease (PAD)

All patients with suspected symptomatic PAD require a comprehensive medical history focusing on exertional leg symptoms (claudication or atypical leg pain), ischemic rest pain, and nonhealing wounds, followed by vascular examination and resting ankle-brachial index (ABI) testing to confirm the diagnosis. 1

Clinical History Assessment

Symptom Evaluation:

• Ask specifically about classic intermittent claudication: reproducible leg pain or discomfort with exertion that stops the patient from walking and resolves within 10 minutes of rest 1
• Screen for atypical leg symptoms (present in 50% of PAD patients): pain that begins at rest but worsens with exertion, pain that doesn't stop walking, or pain that begins with exertion but doesn't resolve within 10 minutes of rest 1
• Inquire about critical limb-threatening ischemia (CLTI) symptoms: ischemic rest pain (especially at night), nonhealing wounds, or gangrene 1
• Note that 40% of PAD patients are asymptomatic but still have functional impairment comparable to those with claudication 1, 2

Risk Factor Documentation:

• Document presence of age ≥65 years, age 50-64 with atherosclerosis risk factors, diabetes with additional risk factors, or known atherosclerotic disease elsewhere 1
• Assess smoking history, hyperlipidemia, hypertension, diabetes mellitus, and chronic kidney disease (three or more risk factors confer 10-fold increased PAD risk) 2

Physical Examination

Vascular Examination (Class I, Level B-NR):

• Pulse palpation of femoral, popliteal, dorsalis pedis, and posterior tibial arteries bilaterally; grade as 0 (absent), 1 (diminished), 2 (normal), or 3 (bounding) 1
• Auscultation for femoral bruits 1
• Bilateral arm blood pressure measurement to identify subclavian stenosis (>15-20 mmHg difference is abnormal) and determine the higher arm pressure for accurate ABI calculation 1

Inspection of Lower Extremities:

• Remove all lower garments, shoes, and socks for thorough examination 1
• Look for hair loss, skin atrophy, dependent rubor, pallor on elevation, cool skin temperature, nonhealing ulcers, and gangrene 1

Diagnostic Testing Algorithm

Initial Test: Resting ABI (Class I, Level B-NR)

Perform resting ABI with or without segmental pressures and waveforms in all patients with history or examination findings suggestive of PAD 1

ABI Interpretation:

• ≤0.90: Abnormal, confirms PAD 1
• 0.91-0.99: Borderline 1
• 1.00-1.40: Normal 1
• >1.40: Noncompressible arteries (suggests medial arterial calcification) 1

Critical Limitation: In symptomatic patients with 50% or greater stenosis on duplex ultrasound, 43% have normal or inconclusive resting ABIs (49% in diabetics, 57% in chronic kidney disease patients) 3. The sensitivity of ABI for detecting significant stenosis is only 57% overall, dropping to 51% in diabetics and 43% in CKD patients 3.

Additional Physiological Testing

For Noncompressible Arteries (ABI >1.40):

• Measure toe-brachial index (TBI) (Class I, Level B-NR); TBI ≤0.70 is abnormal and confirms PAD 1
• TBI has 85% sensitivity and 75% overall accuracy for detecting significant stenosis, maintaining 84% sensitivity in diabetics 3

For Normal/Borderline ABI (>0.90 and ≤1.40) with Exertional Leg Symptoms:

• Perform exercise treadmill ABI testing (Class I, Level B-NR) to unmask PAD and objectively assess functional limitation 1
• A decrease in ABI of >20% or >30 mmHg after exercise confirms PAD 1

For Suspected CLTI with Normal/Borderline ABI:

• Measure TBI with waveforms, transcutaneous oxygen pressure (TcPO₂), or skin perfusion pressure (SPP) (Class IIa, Level B-NR) 1
• CLTI hemodynamic criteria: ankle pressure <50 mmHg, toe pressure <30 mmHg, or TcPO₂ <30 mmHg 1

For Confirmed PAD (ABI ≤0.90) with Nonhealing Wounds:

• TBI with waveforms, TcPO₂, or SPP can be useful to evaluate local perfusion (Class IIa, Level B-NR) 1

Anatomic Imaging (Reserved for Revascularization Candidates)

Perform duplex ultrasound, CTA, or MRA only when revascularization is being considered (Class I, Level B-NR) 1

• Duplex ultrasound is first-line for anatomic characterization and has Class A evidence for diagnosing location and degree of stenosis 1
• Do not perform invasive or noninvasive angiography in asymptomatic PAD patients (Class III, Level B-R) 1

Functional Assessment

For patients with confirmed PAD and claudication:

• Exercise treadmill ABI testing objectively measures functional limitation and response to therapy (Class IIa, Level B-NR) 1
• Six-minute walk test is reasonable for elderly patients or those unable to perform treadmill testing (Class IIb, Level B) 1
• Consider quality of life assessment using validated tools like SF-36 or VascuQoL-6 (Class IIa, Level B) 1

Common Pitfalls to Avoid

• Never rely solely on resting ABI in diabetics or CKD patients—nearly half will have false-negative results despite significant disease 3
• Don't dismiss atypical leg symptoms—50% of PAD patients don't have classic claudication but have comparable functional impairment 1, 2
• Don't order anatomic imaging (CTA/MRA/angiography) for asymptomatic PAD—this is explicitly contraindicated 1
• Don't forget bilateral arm pressures—unequal pressures indicate subclavian stenosis and affect ABI accuracy 1
• In patients with limb-threatening ischemia, recognize that 40% have normal ABIs—proceed to TBI or other perfusion measures 3