What is the recommended diagnostic and therapeutic approach for peripheral arterial disease?

Peripheral Arterial Disease: Diagnostic and Therapeutic Approach

Diagnostic Algorithm

Measurement of the ankle-brachial index (ABI) is the mandatory first-line diagnostic test after clinical examination, with an ABI ≤0.90 confirming the diagnosis of peripheral arterial disease. 1

Initial Clinical Assessment

• Obtain focused history examining for intermittent claudication (reproducible leg pain with exercise, relieved by rest), ischemic rest pain, tissue loss, or ulceration 1
• Recognize that only 10% of PAD patients present with classic claudication symptoms - 50% have atypical leg symptoms and 40% are completely asymptomatic 2, 3
• Identify "masked LEAD" - patients with severe disease but no symptoms due to inability to walk sufficiently (heart failure, diabetic neuropathy, multiple comorbidities) who are at high risk for rapid progression to limb-threatening ischemia 1
• Systematically palpate all pulses (femoral, popliteal, dorsalis pedis, posterior tibial) - weak or absent pulses are the hallmark physical finding 1, 4
• Inspect feet with shoes and socks removed looking for pallor at rest, prolonged capillary refill (>2 seconds), ulcers, or gangrene 1

Objective Testing Sequence

Step 1: Ankle-Brachial Index

• ABI ≤0.90 confirms PAD (75% sensitivity, 86% specificity) 1
• ABI 0.90-1.00 (borderline) requires further testing with post-exercise ABI and/or duplex ultrasound 1
• ABI >1.40 indicates non-compressible vessels (medial calcification) - proceed to alternative testing 1

Step 2: Alternative Tests for Non-Compressible Vessels

• Obtain toe pressure, toe-brachial index (TBI), or Doppler waveform analysis when ABI >1.40 1
• This is particularly critical in patients with diabetes or end-stage chronic kidney disease 1, 2

Step 3: Exercise Testing When Indicated

• Perform treadmill test (Strandness protocol: 3 km/h, 10% slope) when diagnosis is uncertain despite normal resting ABI 1
• Post-exercise ankle pressure decrease >30 mmHg or ABI decrease >20% confirms PAD 1

Step 4: Anatomical Imaging

• Duplex ultrasound (DUS) is the first-line imaging method to confirm lesion location and severity (85-90% sensitivity, >95% specificity for stenosis >50%) 1
• CTA or MRA are indicated for anatomical characterization when revascularization is being considered 1
• Always analyze anatomical imaging in conjunction with symptoms and hemodynamic tests before treatment decisions 1

Therapeutic Approach

Medical Management (All Patients)

Cardiovascular Risk Reduction:

• Prescribe high-intensity statin therapy - improves walking distance and reduces cardiovascular events 1, 2
• Initiate single antiplatelet therapy with clopidogrel (preferred over aspirin) 2
• Optimize blood pressure control with ACE inhibitors or ARBs 1
• Achieve optimal glycemic control in diabetic patients, preferentially using GLP-1 receptor agonists or SGLT-2 inhibitors 1, 2
• Mandate absolute smoking cessation - reduces risk of disease progression, MI, death, and limb ischemia 1

Exercise Therapy:

• Supervised exercise training is the cornerstone of treatment for intermittent claudication (Class I recommendation) 1
• When supervised programs are unavailable, prescribe non-supervised exercise training 1
• Low- to moderate-intensity aerobic activities increase overall and pain-free walking distance 1

Revascularization Indications

Intermittent Claudication:

• Consider revascularization only for lifestyle-limiting claudication that fails to respond to optimal medical therapy and supervised exercise 1, 2
• Endovascular-first strategy for short lesions: <5 cm for aorto-iliac, <25 cm for femoro-popliteal 1
• Bypass surgery for long superficial femoral artery lesions (≥25 cm) when autologous vein available and life expectancy >2 years 1
• Autologous saphenous vein is the conduit of choice for femoro-popliteal bypass 1

Chronic Limb-Threatening Ischemia (CLTI):

• CLTI is defined by ischemic rest pain and/or tissue loss with ankle pressure <50 mmHg or toe pressure <30 mmHg 1
• Early recognition and immediate referral to vascular team is mandatory to improve limb salvage 1
• Revascularization is indicated whenever feasible for limb salvage 1
• Infra-popliteal revascularization using great saphenous vein bypass is indicated 1

Acute Limb Ischemia:

• Urgent revascularization is indicated when neurological deficit is present 1
• Initiate heparin and analgesics immediately 1
• Without neurological deficit, revascularization is indicated within hours after imaging 1

Critical Pitfalls to Avoid

• Never dismiss normal resting ABI when clinical suspicion is high - proceed to post-exercise ABI or duplex ultrasound 1
• Do not overlook "masked LEAD" patients - elderly with multiple comorbidities who cannot walk enough to manifest symptoms but are at high risk for rapid progression 1
• Recognize that primary amputation rates reach 20-25% in patients unsuitable for revascularization, and CLTI confers 3-fold increased risk of MI, stroke, and vascular death 1
• Do not delay revascularization in CLTI - early vascular team involvement is essential 1
• Remember that stem cell/gene therapy is not indicated for CLTI management 1