Peripheral Artery Disease: The Complete Clinical Picture

In short: Peripheral Artery Disease (PAD) is narrowing of the arteries supplying blood to your legs, almost always caused by atherosclerosis — the same plaque buildup process behind heart attacks and strokes. It's common, frequently silent, and significantly underdiagnosed. The reason it matters extends well beyond leg symptoms: PAD is one of the strongest signals that atherosclerosis may be affecting arteries elsewhere in your body too.

What's Actually Happening in the Artery

Atherosclerosis is a systemic disease of the arteries — fatty, fibrous material builds up along the inner artery wall, gradually narrowing the space blood flows through. When this happens in the arteries supplying your legs, it's called PAD. As the artery narrows, muscles downstream don't receive enough blood to meet demand during activity, which is what produces the classic symptom: pain that comes on with walking and eases with rest.

The Spectrum: From Silent to Limb-Threatening

PAD doesn't present the same way in everyone. A substantial portion of people with PAD are asymptomatic — some estimates suggest for every person with symptomatic PAD, there are three to four more with undiagnosed, asymptomatic disease. Among those with symptoms, the classic presentation is intermittent claudication: cramping, aching, or fatigue in the calf, thigh, or buttock brought on by walking, relieved by rest. In more advanced disease, pain can occur even at rest, and in the most severe cases — critical limb ischemia — insufficient blood flow leads to non-healing wounds, and without treatment, limb loss.

Why "No Symptoms" Doesn't Mean "No Risk"

This is the point most people miss entirely: asymptomatic PAD carries meaningfully elevated cardiovascular risk, not just a theoretical future leg problem. Studies show mortality risk roughly doubled in people with asymptomatic PAD compared to age-matched peers without the disease, and more than doubled in those with symptomatic claudication. PAD is frequently a marker of atherosclerosis elsewhere — a large registry found that roughly 60% of PAD patients had atherosclerotic disease in other vascular territories as well, meaning the arteries feeding your heart or brain may be affected too, even if your legs are the only place you've noticed something.

How Common This Actually Is

Prevalence rises sharply with age — around 10% in people over 60, climbing to roughly 20% in people over 75. In high-risk populations (smokers, people with diabetes, prior cardiovascular events), prevalence measured by objective testing runs considerably higher, in some studies affecting more than a quarter of patients screened.

How It's Actually Diagnosed

The ankle-brachial index (ABI) — comparing blood pressure at the ankle to blood pressure at the arm — is the standard first-line test, simple, non-invasive, and reasonably sensitive and specific for significant arterial narrowing. An ABI of 0.9 or below is generally considered diagnostic. For more detailed evaluation of severity or planning treatment, imaging such as duplex ultrasound, CT angiography, or catheter angiography may follow.

What the Evidence Shows

Peripheral vascular disease is estimated to affect roughly 27 million people across Europe and North America. The Fontaine and Rutherford classification systems are the standard tools used to stage PAD severity, from asymptomatic disease through claudication to critical limb ischemia. Critical limb ischemia carries a serious prognosis if untreated — over a third of patients face limb loss within 6 months without intervention.

Vascular Surgeon's Take

The ABI number I actually pay closest attention to isn't just whether it's below 0.9 — it's whether it's above roughly 1.4, which can signal calcified, non-compressible vessels rather than healthy arteries, a pattern I see disproportionately in long-standing diabetics. In that scenario, the test can falsely look reassuring when the underlying disease is actually significant, which is exactly why I don't treat a "normal" ABI as automatically reassuring in every patient.

References
Ankle Brachial Pressure Index (ABPI): An update for practitioners. PMC/British Journal of Community Nursing. doi: 10.2147/vhrm.s6759
Peripheral artery disease: Prevalence and risk factors. UpToDate, 2026.
Management of lower extremity peripheral arterial disease. PubMed, clinical review. DOI: 10.1097/HCR.0b013e31818c3b96
Prevalence of peripheral arterial disease in high-risk patients using ankle-brachial index in general practice, cross-sectional study. DOI: 10.1111/j.1742-1241.2008.01953.x
Epidemiology, diagnosis and classification of peripheral artery disease (PAD). Johns Hopkins University.

Recommended Reading
Leg Pain That Goes Away When You Stop Walking? Here's Why
Up to Half of PAD Cases Have No Symptoms — Here's What to Watch For