Peripheral arterial disease: update of overview and treatment.

Peripheral arterial disease (PAD) is widely used to describe a common disease process in which blood flow to the lower extremities is impaired as a result of atherosclerotic occlusive disease. PAD, an under-diagnosed and under-treated disorder with substantial morbidity and mortality, affects up to 10 million people in the United States. The pathophysiology of peripheral arterial disease and the risk factors for developing PAD are similar to those for atherosclerotic disease occurring at other sites. Risk factors include cigarette smoking, diabetes, dyslipidemia, hypertension, and hyperhomocysteinemia. Peripheral arterial disease can be diagnosed by performing a directed history and physical examination and using a relatively simple, noninvasive screening test, the ankle-brachial index, which measures the severity of the disease and provides valuable prognostic information. Treatments for PAD include medical therapy and endovascular or surgical revascularization. Optimal medical therapy includes claudication pharmacotherapy, participation in a supervised exercise program, tobacco cessation, and modification of treatable risk factors. Patients with lifestyle-limiting claudication who do not respond to medical management or those with critical limb ischemia should be referred to a vascular specialist for potential revascularization. treated in only 25% of affected patients. However, all patients with PAD, whether classic ischemic leg symptoms are present or not, have limited physical activity, impaired walking speed and endurance, and functional decline. Left untreated, PAD can lead to limb amputation. PAD is a strong predictor of systemic atherosclerosis and is considered a coronary artery disease (CAD) risk equivalent. PAD is associated with a fivefold increased risk of heart attack and a twoto threefold greater risk of stroke and total mortality. The 10-year risk of death in people diagnosed with PAD is 40% and has remained largely unchanged since 1950. After multivariate adjustment for age, sex, and other risk factors for cardiovascular disease, patients with PAD had a 3-fold higher risk of all cause death and a 6-fold higher risk of cardiovascular-related death than patients without PAD. The international REACH registry recently evaluated cardiovascular outcomes in more than 68,000 individuals and demonstrated that one in five patients with PAD will suffer a heart attack or stroke, be hospitalized, or die due to cardiovascular events within 1 year. In patients with PAD, the combined rates of heart attack, stroke, and hospitalization are equal to or greater than the rates of those with established coronary artery disease. EPIDEMIOLOGY Approximately 10 million Americans are affected by PAD and as many as 3 million experience claudication, its primary lower extremity ischemic symptom. The estimated prevalence of PAD in people older than 70 years is between 14% and 29%. In addition, PAD is an important manifestation of systemic atherosclerosis, associated with increased rates of cardiovascular ischemic events and death. The prevalence of both PAD and claudication increases with age and exposure to common risk factors, and this prevalence is increasing. In the Framingham Heart Study, the annual incidence of intermittent claudication (IC) in people younger than 44 years was 6 cases per 10,000 person-years in men and 3 cases per 10,000 person-years in women. In people older than 65 years, the annual incidence increased 10 fold, to 61 cases per 10,000 person-years in men and 54 cases per 10,000 person-years in women. Only 10% of patients with PAD have IC, the classic symptom that manifests as a cramping pain in the legs that is induced by exercise and is relieved with rest. Approximately 50% of patients with PAD have atypical lower-extremity symptoms and 40% are asymptomatic. The heterogeneity of clinical presentations may explain why PAD is under-diagnosed and