Peripheral Artery Disease (PAD)
Peripheral artery disease (PAD) is a range of noncoronary arterial syndromes caused by altered structure and function of arteries that supply the brain, visceral organs, and limbs, with atherosclerosis being the most common underlying process affecting the aorta and its branch arteries. 1
Definition and Scope
PAD encompasses disorders that lead to:
- Progressive stenosis or occlusion
- Aneurysmal dilation
- Thromboembolic disease
These processes affect the aorta and its noncoronary branch arteries, including:
- Lower extremity arteries (most common)
- Abdominal aorta
- Renal arteries
- Mesenteric arteries
- Carotid arteries
- Upper extremity arteries
While PAD can affect various arterial beds, it most commonly involves the arteries supplying the lower extremities and the abdominal aorta 1.
Epidemiology
- Affects approximately 8-8.5 million people in the United States 2, 3
- Prevalence is approximately 12% of the adult population 1
- Men are affected slightly more than women 1
- Age-dependent: nearly 20% of adults over 70 years have PAD 1
- Higher prevalence (29%) in high-risk groups:
- Age ≥70 years
- Age 50-69 years with ≥10 pack-year smoking history
- Age 50-69 years with diabetes 1
Clinical Presentation
PAD often goes undiagnosed because of its variable presentation:
- Asymptomatic (up to 50% of patients) 1
- Intermittent claudication (classic symptom but only present in ~33% of patients) 1, 3
- Atypical leg pain (28.5% of patients) 1
- Rest pain (19.1% of patients) 1
- Ischemic ulcers or gangrene (advanced disease)
The Walking and Leg Circulation Study found that among patients with PAD:
- 19.8% had no exertional leg pain
- 28.5% had atypical leg pain
- 32.6% had classic intermittent claudication
- 19.1% had pain at rest 1
Diagnostic Approach
The ankle-brachial index (ABI) is the first-line diagnostic test for PAD 2, 3:
- ABI ≤0.90: Diagnostic of PAD
- ABI 0.91-0.99: Borderline
- ABI 1.0-1.4: Normal
- ABI >1.40: Noncompressible vessels (requires alternative testing)
Additional diagnostic methods include:
- Exercise ABI (if resting ABI normal but symptoms persist)
- Toe-brachial index (for noncompressible vessels)
- Duplex ultrasound
- CT angiography or MR angiography (if revascularization is being considered)
Systemic Implications
PAD is a marker of systemic atherosclerosis and is associated with:
- Increased risk of myocardial infarction
- Increased risk of ischemic stroke
- Increased risk of cardiovascular death
- Overall decreased quality of life and functional capacity 1, 2
Management Approach
Treatment goals include:
- Reducing cardiovascular risk
- Improving leg symptoms and functional capacity
Key interventions:
- Smoking cessation
- Structured exercise therapy
- Antiplatelet therapy (clopidogrel preferred over aspirin) 3
- High-intensity statin therapy
- Blood pressure control
- Diabetes management (particularly with GLP-1 agonists and SGLT-2 inhibitors) 3
- Revascularization for severe disease, critical limb ischemia, or symptoms that don't respond to medical therapy 2
Common Pitfalls
- Underdiagnosis: More than 70% of primary care providers are unaware of PAD in affected patients 1, 2
- Focusing only on leg symptoms while neglecting cardiovascular risk reduction
- Misdiagnosis with pseudoclaudication
- Premature invasive intervention 2
- Failure to recognize that most patients with PAD do not present with classic claudication
PAD represents a significant health burden worldwide, with substantial personal, social, and economic impact. Early diagnosis and comprehensive management are essential to improve quality of life and reduce the risk of cardiovascular events and limb loss.