Lower-Extremity PAD: Epidemiology, Diagnosis, Claudication, Exercise, and Medical Therapy

35.1Definition and presentation

Lower-extremity peripheral artery disease is an atherosclerotic condition characterized by narrowed lower-limb arteries, defined physiologically by a resting ankle-brachial index of <= 0.90 AHA ABI Scientific Statement 2012. Clinical presentation ranges from asymptomatic testing abnormalities to intermittent claudication, chronic limb-threatening ischemia, and acute limb ischemia. Patients frequently present with mixed clinical profiles, including coronary or cerebrovascular atherosclerosis, diabetes, and chronic kidney disease ACC/AHA/SVS 2024.

35.2Epidemiology and risk factors

Lower-extremity peripheral artery disease affects over 8 million adults in the United States and more than 230 million people worldwide AHA Statistics 2024. The disease burden rises sharply with advancing age, particularly over 65 years, and is disproportionately concentrated among Black adults and patients with diabetes or chronic kidney disease. Targeted diagnostic testing is indicated for adults with exertional leg symptoms suggestive of peripheral artery disease and for those at increased risk based on older age, smoking history, diabetes, or established atherosclerotic disease in another vascular bed ACC/AHA/SVS 2024. Routine population screening of asymptomatic adults is not recommended ESC 2017.

35.3Diagnosis and screening

An ankle-brachial index <= 0.90 confirms the diagnosis, demonstrating a sensitivity above 80% and a specificity above 95% compared with angiography AHA ABI Scientific Statement 2012. Accuracy degrades severely with noncompressible vessels. An ankle-brachial index > 1.40 indicates noncompressible arteries, often reflecting medial calcification associated with diabetes or chronic kidney disease, and mandates alternative physiologic assessment such as a toe-brachial index, pulse-volume recording, or duplex ultrasound. A toe-brachial index <= 0.70 is abnormal and confirms the diagnosis in these patients.

35.4Medical therapy and risk reduction

Medical therapy provides systemic atherosclerotic risk reduction and limb protection, and is required for all patients with peripheral artery disease regardless of symptom status ESVS 2024. Core components include blood-pressure control, high-intensity statin therapy, and antiplatelet therapy. Peripheral artery disease confers very-high cardiovascular risk, so lipid lowering targets at least a 50% reduction in LDL cholesterol and an absolute LDL cholesterol below 1.4 mmol/L (55 mg/dL), adding ezetimibe and then a PCSK9 inhibitor when that goal is not met on a statin alone. Statin therapy is associated with lower all-cause mortality in this population, with an observed hazard ratio of 0.72 (95% confidence interval 0.64 to 0.81) in female cohorts Statins Secondary Prevention 2025.

Diabetes management agents carry distinct limb profiles. In the CANVAS trial (n=10,142), canagliflozin reduced major cardiovascular events but increased amputation risk to 6.3 versus 3.4 events per 1000 patient-years (hazard ratio 1.97), necessitating heightened foot vigilance CANVAS (2017). In SUSTAIN-6, semaglutide reduced the composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke from 8.9% to 6.6% (hazard ratio 0.74), though retinopathy complications increased SUSTAIN-6 (2016).

Medical therapy exhibits a severe implementation gap. Meta-analysis of 14,681,801 patients estimates underprescription rates of 28% for antiplatelet therapy, 34% for statins, and 43% for antihypertensives Underprescription Systematic Review 2025. Among patients prescribed antithrombotic regimens, nonadherence approaches one-third, clustering between 2% and 45% depending on measurement methodology Antithrombotic Adherence Review 2025.

35.5Antithrombotic therapy

Antiplatelet monotherapy forms the baseline antithrombotic requirement for symptomatic patients. In the CAPRIE trial (n=19,185), clopidogrel 75 mg daily reduced the annual rate of ischemic stroke, myocardial infarction, or vascular death to 5.32% compared with 5.83% for aspirin 325 mg daily (relative risk reduction 8.7%), with the largest absolute benefit in the symptomatic peripheral artery disease subgroup CAPRIE · 1996.

Dual-pathway inhibition provides intensified treatment for patients at high ischemic risk with acceptable bleeding profiles. In the COMPASS trial (n=27,395), rivaroxaban 2.5 mg twice daily plus aspirin 100 mg daily reduced the composite of cardiovascular death, stroke, or myocardial infarction (4.1% vs 5.4%, hazard ratio 0.76) and major adverse limb events compared with aspirin alone, while major bleeding increased from 1.9% to 3.1% COMPASS · 2017. Following lower-extremity revascularization, the VOYAGER PAD trial (n=6,564) demonstrated that rivaroxaban 2.5 mg twice daily plus aspirin reduced the 3-year composite of acute limb ischemia, major amputation, myocardial infarction, ischemic stroke, or cardiovascular death from 19.9% to 17.3% (hazard ratio 0.85) compared with aspirin alone, with a numerical increase in major bleeding (ISTH hazard ratio approximately 1.4) VOYAGER PAD · 2020.

35.6Claudication management and revascularization

The objective in managing intermittent claudication is functional restoration and cardiovascular risk reduction. Supervised exercise programs serve as first-line therapy, producing sustained improvements in treadmill walking time and distance over follow-up ranging from weeks to two years ESVS 2024 · ESC 2017 · Cochrane Exercise 2014. Compared with non-supervised exercise or walking advice, supervised programs yield approximately 180 meters of additional maximal treadmill walking distance at 3 to 6 months Cochrane Supervised Exercise 2013. A standard program runs sessions of 30 to 45 minutes at least 3 times per week for a minimum of 12 weeks, walking on a treadmill to moderate-to-maximal claudication pain, resting until it resolves, then repeating ACC/AHA/SVS 2024. Cilostazol, a phosphodiesterase-3 inhibitor, has the strongest evidence among drugs for increasing pain-free and maximal walking distance and is offered when exercise and risk-factor control leave symptoms lifestyle-limiting; it is contraindicated in any degree of heart failure. Dose is 100 mg orally twice daily, reduced to 50 mg twice daily when combined with a strong CYP3A4 or CYP2C19 inhibitor.

Revascularization is indicated when lifestyle-limiting symptoms persist despite supervised exercise and optimal medical therapy, or for specific short, proximal lesions where endovascular durability is proven favorable ESVS 2024 · ESC 2017. For aortoiliac claudication, the CLEVER trial (n=111) established that supervised exercise produces superior gains in peak walking time at 6 months (5.8 minutes) compared with primary stenting (3.7 minutes) or optimal medical care alone (1.2 minutes) CLEVER · 2012. When symptoms are lifestyle-limiting and anatomy is suitable for intervention, combined therapy is highly effective. The ERASE trial (n=212) demonstrated that endovascular revascularization plus supervised exercise yielded a greater maximum treadmill walking distance at 12 months than supervised exercise alone (1501 meters vs 1240 meters, mean difference 282 meters) ERASE · 2015.

1. Diagnosis and baseline compressibility are established using a resting ankle-brachial index or toe-brachial index.
2. Core medical therapy (blood-pressure control, a statin, and smoking cessation) and antiplatelet therapy form the baseline treatment for all symptomatic patients.
3. Supervised exercise serves as the primary intervention for intermittent claudication.
4. Revascularization is offered when lifestyle-limiting symptoms persist despite exercise, provided the anatomy is favorable and operative risk is acceptable.
5. Antithrombotic therapy is intensified with dual-pathway inhibition (rivaroxaban and aspirin) post-revascularization or for high-risk profiles with acceptable bleeding risk.
6. Deliberate non-intervention is selected for isolated anatomic disease without symptoms, or for symptomatic patients with prohibitive operative risk.
7. Acute limb ischemia, chronic limb-threatening ischemia, or severe infection moves the patient immediately outside the elective claudication framework into urgent procedural pathways.

35.7Areas of controversy

The future selection of highly specific coagulation targets remains unresolved in clinical practice. Mechanistic evidence demonstrates that inhibiting components of the intrinsic and contact pathways, such as factor XI, factor XII, and prekallikrein, can reduce thrombosis in preclinical models with limited disruption to normal hemostasis Intrinsic Coagulation Review 2019. However, translating these targets into routine, safe antithrombotic regimens for peripheral artery disease lacks definitive clinical trial validation.