The following are key points to remember from this American Heart Association (AHA) Scientific Statement on lower extremity peripheral artery disease (PAD): contemporary epidemiology, management gaps, and future directions:

1. Lower extremity PAD is frequently underdiagnosed and undertreated both in the United States and around the world.
2. To improve awareness and specificity, the term “peripheral artery disease (PAD)” should be used instead of the less specific term “peripheral vascular disease,” which is a larger umbrella term that includes PAD, peripheral venous disease, and lymphatic disease.
3. PAD is severely underrecognized, including by clinicians. In 1999, only one-half of physicians were aware that their patient had a PAD diagnosis, while a recent study found that fewer than two-thirds of primary care clinicians routinely screen for PAD and only 6% were aware of guidelines for PAD treatment.
4. General public awareness of PAD is quite low, ranging from 21-61% across various studies. This likely reflects the variability in nomenclature, variation in clinical presentation, and lack of clinician understanding about prognosis following PAD diagnosis.
5. PAD is the third leading cause of atherosclerotic morbidity, following coronary heart disease and stroke. PAD prevalence ranges from ~5% among people 40-44 years of age up to ~12% of people ages 70-74 years old. There are an estimated 238 million people living with PAD world-wide.
6. Critical limb ischemia (CLI) is a severe form of PAD that includes limb pain at rest, nonhealing wounds, or tissue loss. The 1-year incidence of mortality and amputation is ~20% each for patients with CLI. CLI prevalence is estimated at 1.3%, accounting for 11% of all diagnosed PAD cases.
7. The diagnosis of PAD is made initially with the ankle-brachial index (ABI). An ABI ≤0.9 is considered diagnostic of PAD. For patients with chronic kidney disease, the ABI can be falsely elevated, so a toe-brachial index (TBI) is typically performed and diagnostic of PAD when ≤0.70. Some patients with borderline ABI values may benefit from an exercise ABI test, for which an ABI <0.90 or a drop of >20% is diagnostic of PAD.
8. In 2018, the US Preventive Services Task Force noted that the evidence to support screening at-risk patients was inconclusive. However, the American College of Cardiology/AHA guidelines from 2016 recommend screening high-risk adults with ABI.
9. Important risk factors for PAD include diabetes, tobacco use, hyperlipidemia, and hypertension. Other nontraditional risk factors have been suggested as well, including inflammatory markers (C-reactive protein, interleukin-6), fibrinogen, HIV infection, air pollution, and depression.
10. Many patients with PAD have atypical leg symptoms or report no symptoms because they have restricted their activities. Therefore, clinicians must maintain a high index of suspicion for PAD. Even patients with asymptomatic PAD have poorer functional performance than those without PAD.
11. Acute limb ischemia (ALI), CLI, and amputation are considered the most severe leg outcomes for patients with PAD. However, ALI does not have a standardized definition, making it hard to track for epidemiologic and natural history studies.
12. The presence of PAD is a significant marker for cardiovascular mortality. Patients with an ABI of 0.81-0.90 have a two-fold increase in mortality as compared to patients with a normal ABI. In those with an ABI ≤0.70, mortality risk is four-fold higher. These patients are also at increased risk of coronary heart disease, stroke, and abdominal aortic aneurysm.
13. Despite clear Class I and IIa guideline recommendations for therapies including aspirin, statin, antihypertensives, and tobacco cessation, patients with PAD remain undertreated.
14. Supervised exercise is a first-line, Class I recommendation for patients with PAD. Supervised exercise meaningfully improves walking distance and health-related quality of life. In 2017, the Centers for Medicare & Medicaid Services announced coverage for 12 weeks of supervised exercise. However, most patients are not referred or do not participate.
15. Recent guidelines recommend exercise and medical therapy first-line, with revascularization reserved for refractory cases. However, percutaneous intervention for PAD has increased in utilization. It is important to avoid unnecessary procedures while also offering revascularization to appropriate patients who are also receiving guideline-based medical therapy.

Clinical Topics: Cardiac Surgery, Diabetes and Cardiometabolic Disease, Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Prevention, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Aortic Surgery, Cardiac Surgery and Arrhythmias, Nonstatins, Novel Agents, Statins, Interventions and Vascular Medicine, Exercise, Hypertension

Keywords: Ankle Brachial Index, Antihypertensive Agents, Aortic Aneurysm, Abdominal, Diabetes Mellitus, Exercise, Fibrinogen, HIV Infections, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Hyperlipidemias, Hypertension, Lymphatic Diseases, Myocardial Ischemia, Myocardial Revascularization, Peripheral Arterial Disease, Primary Prevention, Quality of Life, Renal Insufficiency, Chronic, Risk Factors, Stroke, Tobacco Use, Vascular Diseases

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