Chronic Limb Ischaemia (Peripheral Arterial Disease)

1. Clinical Overview

Summary

Chronic limb ischaemia represents the spectrum of peripheral arterial disease (PAD) affecting the lower extremities, ranging from asymptomatic disease through intermittent claudication to critical limb-threatening ischaemia (CLTI). PAD affects over 200 million people worldwide and prevalence increases exponentially with age, affecting 10-20% of adults over 65 years. [1] The condition results from progressive atherosclerotic narrowing of lower limb arteries, leading to inadequate tissue perfusion during exercise (claudication) or at rest (CLTI).

The clinical presentation follows the Fontaine classification: Stage I (asymptomatic), Stage II (intermittent claudication), Stage III (rest pain), and Stage IV (tissue loss with ulceration or gangrene). [2] Ankle-brachial pressure index (ABPI) measurement is the cornerstone diagnostic test, with values less than 0.9 confirming PAD and less than 0.4 indicating severe disease. [3]

PAD is a powerful marker of systemic atherosclerosis. Patients with PAD have cardiovascular mortality rates equivalent to those with established coronary artery disease, with 5-year mortality approaching 20-30%. [4] The majority of PAD patients die from myocardial infarction or stroke rather than limb complications, emphasizing the critical importance of aggressive cardiovascular risk factor modification.

Management combines best medical therapy (antiplatelet agents, high-intensity statins, blood pressure control, diabetes management, and smoking cessation) with supervised exercise therapy for claudication and revascularization (endovascular or surgical bypass) for lifestyle-limiting claudication or CLTI. [5,6] Without intervention, approximately 30% of CLTI patients undergo major amputation within 1 year. [7]

Key Facts

• Global Burden: 200+ million people worldwide; 10-20% of adults > 65 years [1]
• Mortality: 5-year mortality 20-30%, equivalent to many cancers [4]
• Claudication: Reproducible cramping pain in leg muscles during walking, relieved by rest
• CLTI Definition: Rest pain > 2 weeks OR tissue loss (ulcer/gangrene) AND ABPI less than 0.5 OR ankle pressure less than 50mmHg [8]
• Diagnostic Test: ABPI less than 0.9 = PAD; less than 0.4 = severe/critical disease [3]
• Primary Risk: Cardiovascular death (MI/stroke) exceeds limb loss
• Treatment Pillar: Smoking cessation reduces amputation risk by 50% [9]
• Exercise Efficacy: Supervised exercise increases walking distance by 50-200% [10]

Clinical Pearls

"PAD = CAD Equivalent": Patients with PAD have the same cardiovascular risk as those with established coronary artery disease. Aggressive risk factor modification is mandatory, not optional.

"Claudication Distance is the Metric": Unlike arthritic or neurogenic pain, claudication occurs at a reproducible walking distance. Document the claudication distance in meters at every visit.

"ABPI: Quick, Cheap, Underutilized": ABPI measurement takes 10-15 minutes and confirms diagnosis. ABPI > 1.3 suggests calcified, incompressible vessels (common in diabetes and chronic kidney disease) - use toe pressures instead.

"Smoking Cessation is THE Intervention": More powerful than any medication or procedure. Continued smoking after revascularization increases re-stenosis, graft failure, and amputation rates by 2-3 fold. [9]

"Buerger's Test Still Matters": Leg pallor on 45° elevation with rubor on dependency indicates severe ischaemia. Simple bedside test that predicts critical disease.

"Most Claudicants Remain Stable": 70-80% of claudication patients remain stable or improve with medical therapy and exercise alone. Only 10-20% progress to CLTI over 5-10 years. [11]

"Diabetes Changes Everything": Diabetic patients develop more distal (tibial) disease, calcified vessels (falsely elevated ABPI), and worse wound healing. Tissue loss is more common than classic claudication.

Why This Matters Clinically

PAD is fundamentally a cardiovascular disease, not just a leg problem. The atherosclerotic burden in leg arteries mirrors disease in coronary, carotid, and renal circulations. Early detection through ABPI screening in high-risk populations (smokers, diabetics, age > 65) enables cardiovascular risk stratification and intervention before major adverse events occur.

The societal burden is substantial: PAD reduces quality of life through pain and functional limitation, generates high healthcare costs through revascularization procedures and amputations, and causes premature death. Amputation carries devastating consequences - 30-day mortality of 5-10%, with 50% 5-year mortality and 10% annual risk of contralateral amputation. [12]

Effective management requires multidisciplinary collaboration: primary care physicians for risk factor control, vascular surgeons for revascularization, podiatrists for foot care, and rehabilitation specialists for supervised exercise programs.

---

2. Epidemiology

Global Prevalence

PAD affects over 200 million people worldwide, with prevalence varying by geography, ethnicity, and socioeconomic status. [1] In high-income countries, prevalence ranges from 10-20% in adults over 65 years, increasing to 15-20% in those over 80 years. The true prevalence is likely underestimated due to asymptomatic disease in 40-50% of affected individuals.

Age Distribution

Sex Differences

• Overall: Male predominance (M:F ratio approximately 2:1) [1]
• Younger patients (less than 60 years): Male predominance more pronounced
• Older patients (> 80 years): Sex ratio equalizes
• CLTI presentation: Women tend to present later with more advanced disease
• Post-intervention outcomes: Women have higher perioperative complications and lower long-term patency rates in some studies [13]

Ethnic and Racial Variation

Socioeconomic Factors

• Deprivation: Strong inverse correlation with socioeconomic status
• Education: Lower educational attainment associated with higher PAD prevalence
• Healthcare Access: Delayed presentation and worse outcomes in underserved populations
• Smoking: Higher smoking rates in lower socioeconomic groups drive PAD disparity

Risk Factors

Non-Modifiable Risk Factors

Modifiable Risk Factors

Smoking and PAD

• Dose-Response: Risk increases with pack-years
• Type: Cigarettes > cigars, pipes
• Environmental: Passive smoking also increases risk
• Cessation Benefit: Risk reduction begins within 1 year, but never returns to baseline [9]

Diabetes and PAD

• Prevalence: PAD affects 20-30% of diabetics
• Pattern: More distal (tibial) disease, medial arterial calcification
• Complications: Neuropathy masks claudication; tissue loss more common than classic claudication
• Outcomes: Higher amputation rates, worse wound healing [15]

Natural History

Claudication (Fontaine Stage II)

• Stable: 70-80% remain stable or improve over 5 years [11]
• Progression to CLTI: 10-20% over 5-10 years
• Annual amputation rate: 1-2%
• 5-year survival: 70-80%

Critical Limb-Threatening Ischaemia (CLTI)

• Without revascularization: 30% undergo major amputation at 1 year [7]
• Cardiovascular events: 20% die within 1 year from MI/stroke
• 5-year survival: 40-50%

Asymptomatic PAD (Fontaine Stage I)

• Progression: 15-20% develop claudication over 5 years
• Cardiovascular events: Similar event rates to symptomatic PAD
• Importance: Identifies high-risk individuals for intensive risk factor modification

---

3. Pathophysiology

Atherosclerotic Process

PAD results from progressive atherosclerosis of lower limb arteries. The pathophysiological cascade mirrors coronary and carotid atherosclerosis:

Endothelial Dysfunction

1. Initiation: Endothelial injury from shear stress, oxidized LDL, smoking toxins, hyperglycemia
2. Inflammation: Adhesion molecule expression (VCAM-1, ICAM-1) recruits monocytes/macrophages
3. Lipid Accumulation: Subendothelial LDL oxidation and foam cell formation
4. Smooth Muscle Proliferation: Migration from media to intima

Plaque Development

• Fatty Streak: Early lesion (reversible)
• Fibrous Plaque: Lipid core with fibrous cap
• Complicated Plaque: Calcification, intraplaque hemorrhage, ulceration
• Critical Stenosis: > 50% diameter stenosis causes hemodynamic significance

Thrombotic Complications

• Plaque Rupture: Exposes thrombogenic core
• Acute Thrombosis: Can convert chronic stable disease to acute limb ischaemia
• Microembolization: "Blue toe syndrome" from cholesterol emboli

Hemodynamic Principles

Pressure-Flow Relationships

Poiseuille's Law: Flow ∝ (Pressure gradient × Radius⁴) / (Viscosity × Length)

Key implications:

• Radius is Critical: Halving vessel radius reduces flow by 16-fold
• Stenosis Threshold: > 50% diameter stenosis (75% area) causes hemodynamic significance
• Serial Stenoses: Multiplicative effect on flow reduction
• Collateral Compensation: Can maintain resting flow despite occlusion

Resting vs Exercise Hemodynamics

Why Claudication Occurs

1. At Rest: Collateral vessels provide adequate perfusion for baseline metabolic needs
2. With Exercise: Muscle oxygen demand increases 10-20 fold; fixed stenosis prevents proportional flow increase
3. Metabolite Accumulation: Lactate, adenosine, and other metabolites accumulate in ischaemic muscle, causing pain
4. Rest Relief: Cessation of exercise allows repayment of oxygen debt and metabolite clearance (typically 2-3 minutes)

Critical Limb Ischaemia Pathophysiology

CLTI occurs when arterial perfusion is insufficient to meet resting metabolic demands:

• Perfusion Pressure: Falls below critical threshold (~40-50 mmHg ankle pressure)
• Rest Pain: Ischaemic neuritis in distal nerves; worse at night when cardiac output and perfusion pressure drop
• Tissue Loss: Impaired oxygen delivery prevents wound healing; minor trauma leads to non-healing ulcers
• Gangrene: Complete tissue necrosis due to absent perfusion

Anatomical Distribution

Aortoiliac Disease (30%)

Typical Patient: Younger smoker (40-60 years), often male

Clinical Features:

• Buttock and thigh claudication
• Erectile dysfunction (Leriche syndrome)
• Absent femoral pulses
• Reduced femoral-brachial pressure index

Leriche Syndrome Triad:

1. Buttock/thigh claudication
2. Erectile dysfunction
3. Absent femoral pulses

Femoropopliteal Disease (50%)

Typical Patient: Most common pattern; age 60-75 years

Clinical Features:

• Calf claudication (gastrocnemius)
• Palpable femoral pulse
• Absent popliteal and distal pulses
• Superficial femoral artery (SFA) most commonly affected

Tibial/Infrapopliteal Disease (20%)

Typical Patient: Diabetics, chronic kidney disease patients

Clinical Features:

• Foot claudication (less common than ischaemic ulcers)
• Palpable popliteal pulse
• Absent pedal pulses
• Medial arterial calcification common
• High risk for tissue loss and amputation

Multi-Level Disease

• Prevalence: 40-50% of PAD patients have disease at multiple levels
• Outcomes: Worse prognosis for limb salvage
• Revascularization: Often requires hybrid (endovascular + surgical) approach

Collateral Development

The extent and rapidity of collateral vessel development determines symptom severity:

Microvascular Dysfunction

Beyond macrovascular stenosis, PAD involves:

• Endothelial Dysfunction: Reduced nitric oxide bioavailability
• Impaired Vasodilation: Blunted hyperemic response
• Capillary Rarefaction: Reduced capillary density in ischaemic muscle
• Mitochondrial Dysfunction: Impaired oxidative metabolism even with adequate flow

---

4. Clinical Presentation

Fontaine Classification

The Fontaine classification stages PAD by symptom severity:

Rutherford Classification

The Rutherford classification provides more granular staging:

Intermittent Claudication

Cardinal Features

Site and Stenosis Level

Severity Assessment

Walking Distance:

• Mild: > 300 meters
• Moderate: 100-300 meters
• Severe: less than 100 meters

Impact on Activities:

• Shopping, household tasks, employment
• Recreational activities, social participation
• Quality of life impairment

Critical Limb-Threatening Ischaemia (CLTI)

Diagnostic Criteria

CLTI is defined by rest pain for > 2 weeks OR tissue loss (ulcer/gangrene) AND objective hemodynamic criteria: [8]

Rest Pain Characteristics

Pathophysiology: Ischaemic neuritis from inadequate perfusion of peripheral nerves.

Tissue Loss

Ulceration:

• Location: Toes, heel, malleoli (pressure points)
• Appearance: Punched-out, pale or necrotic base
• Pain: Severe (vs venous ulcers which are less painful)
• Healing: Poor or absent without revascularization

Gangrene:

• Dry Gangrene: Mummified, black, demarcated; minimal infection risk
• Wet Gangrene: Infected, purulent, spreading; medical emergency
• Pattern: Often starts in toes, may progress proximally

CLTI Prognosis

Without revascularization:

• Major amputation: 30% at 1 year [7]
• Death: 20% at 1 year
• Amputation-free survival: 50% at 1 year

Distinguishing PAD from Other Causes of Leg Pain

Asymptomatic PAD

Prevalence: 40-50% of individuals with ABPI less than 0.9 are asymptomatic

Why Asymptomatic:

• Sedentary lifestyle (insufficient exercise to provoke symptoms)
• Well-developed collaterals
• Gradual progression allowing adaptation
• Coexisting conditions limiting activity (arthritis, cardiac disease)

Clinical Significance:

• Same cardiovascular risk as symptomatic PAD [4]
• Requires aggressive risk factor modification
• 15-20% develop symptoms over 5 years

Atypical Presentations

Diabetic PAD

• Neuropathy masks claudication: Pain sensation blunted
• Tissue loss without claudication: First presentation may be ulcer or infection
• Medial arterial calcification: Falsely elevated ABPI
• Poor wound healing: Minor trauma leads to non-healing ulcers

Acute-on-Chronic Ischaemia

• Presentation: Sudden worsening of chronic symptoms; new rest pain
• Mechanism: Thrombosis of pre-existing stenosis or plaque rupture
• Urgency: Requires urgent vascular assessment
• 6 Ps (if complete occlusion): Pain, Pallor, Pulselessness, Paraesthesia, Paralysis, Perishingly cold

Blue Toe Syndrome

• Presentation: Purple/blue discoloration of toes with palpable pulses
• Mechanism: Cholesterol or thrombotic microembolization from proximal plaque
• Source: Aorta, iliac arteries, or popliteal aneurysm
• Significance: Indicates unstable plaque; risk of recurrent embolization

---

5. Clinical Examination

Systematic Approach

Inspection

General Assessment:

• Nutritional status: Muscle wasting suggests chronic ischaemia
• Mobility: Observe gait and walking aids
• Footwear: Ill-fitting shoes cause pressure ulcers in ischaemic feet

Skin Changes:

• Colour:

  • Pallor (pale, white) suggests severe ischaemia
  • Rubor (dependent redness) indicates compensatory vasodilation
  • Cyanosis (blue) suggests venous congestion or microembolization
  • Mottling indicates poor perfusion

• Hair Loss: Loss of leg/foot hair (not specific but supportive)

• Skin Texture: Shiny, thin, atrophic skin

• Temperature: Cool or cold to touch

Trophic Changes:

• Nails: Thickened, dystrophic, slow-growing
• Muscle: Calf or foot muscle wasting
• Fat Pads: Loss of plantar fat pads

Ulceration:

• Arterial Ulcers:

  • "Location: Toes, heel, malleoli, pressure points"
  • "Appearance: Punched-out, pale or necrotic base, well-demarcated edges"
  • "Pain: Severe"
  • "Surrounding skin: Pale, cool"

• Venous Ulcers (for comparison):

  • "Location: Gaiter area (medial malleolus)"
  • "Appearance: Shallow, irregular edges, granulating base"
  • "Pain: Less severe"
  • "Surrounding skin: Pigmentation, eczema, oedema"

Gangrene:

• Dry: Black, mummified, demarcated
• Wet: Purulent, swollen, spreading (surgical emergency)

Palpation

Temperature:

• Method: Back of hand, compare both limbs side-to-side
• Pattern: Progressive cooling distally suggests arterial insufficiency
• Caution: Room temperature affects assessment

Capillary Refill Time (CRT):

• Method: Press nail bed for 5 seconds, release, observe refill
• Normal: less than 2 seconds
• Prolonged: > 2-3 seconds suggests poor perfusion
• Limitation: Affected by temperature, peripheral neuropathy

Peripheral Pulses:

Palpate systematically and grade:

• 0: Absent
• 1: Diminished
• 2: Normal
• 3: Bounding (aneurysmal?)

Pulse Patterns and Stenosis Localization:

Auscultation:

• Bruits: Turbulent flow through stenosis
• Sites: Aorta, iliac, femoral arteries
• Significance: Indicates stenosis (but absence doesn't exclude disease)

Special Tests

Buerger's Test

Technique:

1. Elevation: Patient supine, elevate leg to 45° for 60 seconds
2. Observe: Note color change in foot
3. Dependency: Sit patient up, hang legs over bed edge
4. Observe: Note color change and venous filling time

Interpretation:

• Normal: Minimal color change; venous filling less than 15 seconds
• Moderate Ischaemia: Pallor on elevation; rubor on dependency; venous filling 15-30 seconds
• Severe Ischaemia: Pallor on elevation (less than 30 seconds); marked rubor on dependency; venous filling > 30 seconds

Buerger's Angle:

• Angle at which foot becomes pale on elevation
• Normal: > 90° (no pallor even when vertical)
• Severe ischaemia: less than 20° (pale even at slight elevation)

Ankle-Brachial Pressure Index (ABPI)

Equipment:

• Hand-held Doppler probe (8 MHz for peripheral arteries)
• Sphygmomanometer with appropriately sized cuff
• Ultrasound gel

Technique:

1. Patient Position: Supine, rested for 5-10 minutes
2. Brachial Pressure: Measure systolic BP in both arms (use higher value)
3. Ankle Pressure: Measure systolic pressure in:
   • Dorsalis pedis artery (dorsum of foot)
   • Posterior tibial artery (behind medial malleolus)
4. Use higher ankle pressure from each leg
5. Calculate: ABPI = Ankle Pressure / Brachial Pressure

Interpretation:

Limitations:

• Medial Arterial Calcification: Falsely elevated ABPI (> 1.3) in diabetes, CKD, elderly
  • "Alternative: Toe-brachial pressure index (TBPI)"
• Acute Limb Ischaemia: ABPI unhelpful in acute setting
• Bilateral Upper Limb Disease: May underestimate disease severity

Toe Pressures and Toe-Brachial Index (TBPI)

Indication: Non-compressible vessels (ABPI > 1.3)

Technique:

• Small cuff on great toe
• Photoplethysmography or Doppler to detect pulse

Interpretation:

• Normal: Toe pressure > 70 mmHg; TBPI > 0.7
• PAD: Toe pressure less than 70 mmHg; TBPI less than 0.7
• CLTI: Toe pressure less than 30 mmHg

Exercise ABPI

Indication:

• Suspected PAD with normal resting ABPI
• Borderline ABPI (0.9-1.0) with typical symptoms

Technique:

1. Measure resting ABPI
2. Exercise patient (treadmill or heel raises) until claudication occurs
3. Measure ankle pressure immediately post-exercise and at 1-minute intervals

Interpretation:

• Normal: ABPI unchanged or increases slightly
• PAD: ABPI falls by > 20% or > 30 mmHg
• Recovery: Delayed recovery to baseline (> 3-5 minutes) suggests PAD

Neurological Examination

Sensation:

• Light touch: Cotton wool or finger
• Vibration: 128 Hz tuning fork
• Proprioception: Toe position sense
• Pain/Temperature: Pinprick

Significance:

• Neuropathy: Common in diabetics; masks ischaemic pain
• Pattern: "Glove and stocking" distribution in diabetes
• Intersection: PAD + neuropathy = high amputation risk

Motor:

• Power: Test dorsiflexion, plantarflexion
• Wasting: Intrinsic foot muscles
• Acute Ischaemia: Paralysis suggests irreversible muscle ischaemia

Wound Assessment

For patients with ulceration:

Size: Measure length × width × depth

Location: Pressure points (heel, malleoli, metatarsal heads) suggest arterial

Base:

• Necrotic (black eschar)
• Sloughy (yellow fibrin)
• Granulating (red)

Edges:

• Punched-out (arterial)
• Undermined (pressure/diabetic)
• Irregular (venous)

Surrounding Tissue:

• Cellulitis (erythema, warmth, oedema)
• Gangrene
• Exposed bone/tendon

Exudate: Amount, color, odor

Infection Signs:

• Purulent discharge
• Foul odor
• Spreading erythema
• Systemic signs (fever, tachycardia)

---

6. Investigations

First-Line Non-Invasive Tests

Ankle-Brachial Pressure Index (ABPI)

Indications:

• Suspected PAD based on history/examination
• Screening in high-risk populations (age > 65, smokers, diabetics)
• Cardiovascular risk stratification

Advantages:

• Quick (10-15 minutes)
• Non-invasive
• Inexpensive
• High sensitivity and specificity for PAD [3]

Diagnostic Accuracy:

• Sensitivity: 75-90% for detecting > 50% stenosis
• Specificity: 85-95%

Duplex Ultrasound

Technique:

• B-mode imaging: Visualizes arterial anatomy
• Doppler: Assesses blood flow velocity and direction
• Color flow: Displays flow direction and turbulence

Information Provided:

• Stenosis location and severity
• Occlusion vs stenosis
• Calcification
• Plaque morphology
• Collateral pathways

Stenosis Grading:

Advantages:

• Non-invasive
• No radiation
• No contrast
• Can assess stenosis severity

Limitations:

• Operator-dependent
• Difficult in obese patients
• Calcification causes acoustic shadowing
• Limited assessment of aortoiliac and tibial vessels

Role: First-line imaging for anatomical assessment before considering revascularization

Advanced Imaging

CT Angiography (CTA)

Technique:

• Contrast-enhanced multi-detector CT
• Arterial phase imaging from aorta to feet
• Multiplanar reconstructions

Advantages:

• Excellent visualization of aortoiliac and infrainguinal vessels
• Assesses calcification burden
• Evaluates collaterals
• Fast acquisition
• Defines anatomy for surgical/endovascular planning

Disadvantages:

• Ionizing radiation
• Iodinated contrast (nephrotoxicity risk)
• Overestimates stenosis in heavily calcified vessels
• Artifacts from metallic stents/clips

Contrast Nephropathy Risk:

• Higher risk in CKD (eGFR less than 30), diabetes, volume depletion
• Mitigation: IV hydration, minimize contrast volume, avoid repeat studies within 48 hours

MR Angiography (MRA)

Techniques:

• Contrast-Enhanced MRA (CE-MRA): Gadolinium-based contrast
• Non-Contrast MRA: Time-of-flight, phase-contrast techniques

Advantages:

• No ionizing radiation
• Excellent soft tissue contrast
• Assesses vessel wall pathology
• Less nephrotoxic than iodinated contrast (gadolinium)

Disadvantages:

• Overestimates stenosis severity
• Artifacts from metallic implants (stents, joint replacements)
• Longer acquisition time
• Claustrophobia
• Expensive
• Contraindications: Pacemakers, ICDs, metallic implants (some)

Gadolinium Considerations:

• Nephrogenic Systemic Fibrosis (NSF): Rare but serious; avoid in severe CKD (eGFR less than 30) with older gadolinium agents
• Newer agents: Lower NSF risk but still caution in renal impairment

Digital Subtraction Angiography (DSA)

Technique:

• Invasive arterial catheterization
• Iodinated contrast injection
• Serial X-ray imaging with digital subtraction

Status: Gold standard for anatomical assessment

Advantages:

• Highest spatial resolution
• Dynamic flow assessment
• Allows simultaneous intervention (angioplasty, stent, atherectomy)
• Pressure gradient measurement across stenoses

Disadvantages:

• Invasive (arterial puncture)
• Ionizing radiation
• Iodinated contrast (nephrotoxicity)
• Complications: Bleeding, dissection, embolization, access site injury (1-2%)

Current Role: Reserved for patients undergoing endovascular intervention, not for diagnosis alone

Functional/Physiological Tests

Transcutaneous Oxygen Tension (TcPO₂)

Technique:

• Heated electrode on foot/forefoot skin
• Measures oxygen diffusion through skin

Interpretation:

• Normal: > 40 mmHg
• Borderline: 30-40 mmHg
• CLTI: less than 30 mmHg
• Healing Unlikely: less than 20 mmHg

Clinical Uses:

• Predict wound healing potential
• Guide amputation level selection
• Assess revascularization success

Exercise Treadmill Testing

Protocols:

• Constant: Fixed speed/grade until claudication (assess claudication distance)
• Graded: Progressive speed/gradient (assess maximal walking distance)

Measurements:

• Absolute Claudication Distance (ACD): Distance at which patient must stop
• Initial Claudication Distance (ICD): Distance at onset of pain
• Post-Exercise ABPI: Assess hemodynamic significance

Clinical Use:

• Establish baseline functional capacity
• Assess treatment response (exercise program, revascularization)
• Differentiate PAD from other causes of leg pain

Cardiovascular Assessment

PAD is a marker of systemic atherosclerosis. Assess for coexistent disease:

Cardiac Evaluation

Prevalence of Coexistent CAD: 40-60% of PAD patients have significant coronary disease [16]

Carotid Assessment

Prevalence of Carotid Stenosis: 15-25% of PAD patients have > 50% carotid stenosis [16]

Laboratory Tests

Baseline Blood Tests

Specialized Tests (Selected Cases)

---

7. Management

Management of PAD follows a tiered approach: universal cardiovascular risk factor modification (best medical therapy) for all patients, plus symptom-directed interventions (exercise therapy for claudication, revascularization for CLTI or lifestyle-limiting claudication).

Best Medical Therapy (ALL Patients)

Best medical therapy (BMT) is the foundation of PAD management and is indicated for ALL patients regardless of symptom severity:

1. Smoking Cessation

Evidence: Smoking cessation is the single most effective intervention in PAD. Continued smoking increases:

• Amputation risk by 50% [9]
• Graft failure rates by 2-3 fold
• Progression to CLTI
• Cardiovascular mortality

Approach:

Target: Complete cessation. No safe level of smoking.

2. Antiplatelet Therapy

Evidence: Reduces major adverse cardiovascular events (MACE) by 20-25% in PAD patients [17]

First-Line Options:

Enhanced Regimens (Selected High-Risk Patients):

Contraindications: Active bleeding, high bleeding risk, recent hemorrhagic stroke

3. High-Intensity Statin Therapy

Evidence: Reduces cardiovascular events by 20-30% and may slow PAD progression [20]

Regimen:

Monitoring: Baseline and 3-month lipids and liver function

Additional Therapy (if target not achieved):

• Ezetimibe 10 mg daily (add to statin)
• PCSK9 Inhibitors (evolocumab, alirocumab) if LDL remains > 1.4 mmol/L on maximal statin + ezetimibe

4. Blood Pressure Control

Target: less than 140/90 mmHg (or less than 130/80 mmHg if tolerated without symptoms) [5]

Preferred Agents:

Avoid:

• Beta-Blockers: Theoretical concern for worsening claudication (but meta-analyses show no significant harm; use if clear indication like post-MI, heart failure)

5. Diabetes Control

Target: Individualized HbA1c (typically less than 53 mmol/mol [7%] if safely achievable)

Agents with Cardiovascular Benefit:

Foot Care in Diabetics:

• Daily foot inspection
• Podiatry referral
• Appropriate footwear
• Avoid barefoot walking

6. Anticoagulation (Selected Patients)

Indications:

• Atrial fibrillation (CHA₂DS₂-VASc score ≥2): Anticoagulation with DOAC or warfarin
• Post-bypass grafting: Some advocate for anticoagulation in infrainguinal vein grafts (controversial; case-by-case)

Claudication-Specific Management

Supervised Exercise Therapy (SET)

Evidence: Cochrane review shows SET increases:

• Maximum walking distance by 120-180 meters [10]
• Pain-free walking distance by 80-100 meters
• Quality of life

Prescription:

• Frequency: 3 sessions per week
• Duration: 30-45 minutes per session
• Program Length: Minimum 12 weeks (optimal 6 months)
• Intensity: Walk to near-maximal claudication pain, rest, repeat
• Supervision: Trained exercise physiologist or physiotherapist

Mechanism:

• Improved collateral circulation
• Enhanced muscle metabolism and oxygen extraction
• Increased mitochondrial density
• Improved endothelial function

Efficacy: Comparable to revascularization for improving walking distance in many patients [22]

Barriers:

• Availability (limited programs in many regions)
• Patient adherence
• Funding/insurance coverage

Home Exercise (if SET unavailable):

• Less effective than supervised programs
• Provide walking prescription (30-45 min, 5×/week, walk to claudication)

Pharmacotherapy for Claudication

NOTE: Pentoxifylline, once popular, shows minimal benefit in meta-analyses and is no longer recommended.

Revascularization for Claudication

Indications:

• Lifestyle-limiting claudication despite optimal medical therapy and exercise program (typically 3-6 months)
• Patient preference after informed discussion
• Favorable anatomy for intervention

NOT indicated for:

• Mild claudication with adequate quality of life
• Patients who have not attempted exercise therapy
• High surgical risk with mild symptoms

Critical Limb-Threatening Ischaemia (CLTI) Management

CLTI is a limb- and life-threatening emergency requiring urgent vascular assessment and revascularization evaluation.

Immediate Management

Urgent Vascular Assessment

Imaging:

• Duplex Ultrasound: Initial assessment
• CTA or MRA: Anatomical roadmap for revascularization planning
• DSA: If proceeding directly to endovascular intervention

Multidisciplinary Team:

• Vascular surgeon
• Interventional radiologist
• Podiatrist
• Diabetologist (if diabetic)
• Wound care specialist

Revascularization Decision

Aim: Restore straight-line arterial flow to the foot (at least one tibial artery) [24]

Options:

Endovascular Revascularization

Techniques:

• Angioplasty ± Stent: Balloon dilatation of stenosis/occlusion
• Atherectomy: Plaque excision (orbital, laser, directional)
• Drug-Eluting Balloon/Stent: Reduce restenosis

Advantages:

• Less invasive
• Local/regional anaesthesia
• Shorter recovery
• Repeatable
• Suitable for high-risk patients

Disadvantages:

• Higher re-stenosis rates (30-50% at 1 year for femoropopliteal lesions)
• Less durable than bypass
• May not be technically feasible (chronic total occlusions, heavy calcification)

Best Results:

• Short stenoses (less than 10 cm)
• Aortoiliac disease
• Patients unfit for surgery

Surgical Bypass

Techniques:

Advantages:

• More durable patency
• Better for long occlusions, multi-level disease
• Gold standard for CLTI with suitable anatomy

Disadvantages:

• Invasive (general/spinal anaesthesia)
• Longer recovery
• Higher perioperative morbidity/mortality
• Requires suitable vein conduit

Vein Harvest:

• Great Saphenous Vein (GSV): Best conduit
• Alternate Veins: Small saphenous, arm veins if GSV unavailable

Hybrid Procedures

Definition: Combination of endovascular and open surgical techniques in same procedure

Example: Common femoral endarterectomy + SFA angioplasty/stent

Advantage: Tailored approach for complex multi-level disease

BEST-CLI Trial (2022) [24]

Design: Randomized trial comparing endovascular vs surgical bypass in CLTI

Findings:

• Cohort 1 (adequate saphenous vein): Surgery superior to endovascular (lower amputation/death)
• Cohort 2 (no adequate vein): Endovascular preferred (prosthetic bypass inferior)

Implication: Best revascularization strategy depends on anatomy and conduit availability; surgical bypass with vein is optimal if feasible.

Amputation

Indications:

• Absolute: Irreversible ischaemia (muscle necrosis, fixed paralysis, anaesthesia)
• Relative: Extensive tissue loss not amenable to revascularization, patient preference, non-ambulatory status

Levels:

• Minor Amputation: Toe, ray, transmetatarsal (preserves ambulation)
• Major Amputation: Below-knee (BKA) or above-knee (AKA)

Considerations:

• BKA vs AKA: BKA preserves knee, better rehabilitation; requires adequate below-knee perfusion (TcPO₂ > 30-40 mmHg)
• Rehabilitation: Early prosthetic fitting, physiotherapy
• Psychological Support: Counseling, peer support

Outcomes:

• 30-day mortality: 5-10%
• 1-year survival: 70-80% (BKA); 60-70% (AKA)
• Mobility: 50-60% achieve independent ambulation with prosthesis
• Contralateral amputation: 10% per year

Novel Therapies (Emerging/Investigational)

---

8. Complications

Limb Complications

Progression to CLTI

• Incidence: 10-20% of claudicants over 5-10 years [11]
• Risk Factors: Continued smoking, diabetes, multi-level disease, low ABPI

Acute Limb Ischaemia

• Mechanism: Thrombosis of pre-existing stenosis, embolization, graft thrombosis
• Presentation: 6 Ps (Pain, Pallor, Pulselessness, Paraesthesia, Paralysis, Perishingly cold)
• Management: Emergency revascularization (thrombolysis, thrombectomy, bypass)
• Outcome: Without intervention, limb loss in 6-12 hours

Amputation

• Major Amputation Rate: 1-2% per year in claudicants; 30% at 1 year in untreated CLTI [7]
• Complications: Wound infection, stump non-healing, phantom limb pain, psychological distress

Chronic Pain

• Rest Pain: Requires opioid analgesia; severely impairs quality of life
• Neuropathic Pain: Ischaemic neuropathy, post-amputation phantom pain

Cardiovascular Complications

PAD patients have elevated risk for systemic atherosclerotic events:

Myocardial Infarction

• Incidence: 2-4% per year [4]
• Leading Cause of Death: 40-50% of PAD patients die from CAD
• Risk Stratification: Consider cardiac stress testing before major vascular surgery

Stroke

• Incidence: 1-2% per year
• Multi-Territory Disease: 15-25% of PAD patients have carotid stenosis [16]

Cardiovascular Mortality

• 5-year Mortality: 20-30% [4]
• CLTI Patients: 20% 1-year mortality, 50% 5-year mortality
• Comparison: Similar to many cancers

Revascularization Complications

Endovascular Complications

Surgical Complications

---

9. Prognosis & Outcomes

Claudication Prognosis

Natural History (with best medical therapy):

• Stable or Improved: 70-80% at 5 years [11]
• Progression to CLTI: 10-20% over 5-10 years
• Major Amputation: 1-2% per year
• 5-year Survival: 70-80%

Factors Predicting Stability:

• Smoking cessation
• Good medication adherence
• Mild baseline symptoms (long claudication distance)
• Single-level disease

Factors Predicting Progression:

• Continued smoking
• Diabetes (especially poor control)
• Low ABPI (less than 0.5)
• Multi-level disease
• Chronic kidney disease

CLTI Prognosis

Without Revascularization:

• Major Amputation: 30% at 1 year [7]
• Death: 20% at 1 year
• Amputation-Free Survival: 50% at 1 year

With Revascularization:

• Limb Salvage: 70-80% at 1 year
• Death: 10-15% at 1 year (perioperative + cardiovascular)
• 5-year Survival: 40-50%

Factors Predicting Limb Salvage:

• Successful revascularization (patent graft/angioplasty)
• Tissue loss limited (minor vs extensive gangrene)
• Infection control
• Smoking cessation
• Adequate wound care

Post-Revascularization Outcomes

Endovascular Revascularization

Primary Patency (vessel remains open without re-intervention):

Factors Affecting Patency:

• Lesion length (short better than long)
• Stenosis vs occlusion (stenosis better)
• Runoff quality (good distal vessels improve patency)
• Diabetes (lower patency)

Surgical Bypass

Primary Patency:

Vein vs Prosthetic:

• Vein: Superior patency at all time points
• Prosthetic: Acceptable for above-knee bypasses; poor for below-knee/distal

Secondary Patency (patency after intervention for stenosis): 10-15% higher than primary patency

Post-Amputation Outcomes

Mortality:

• 30-day: 5-10%
• 1-year: 20-30%
• 5-year: 40-50%

Functional Outcomes:

• Independent Ambulation: 50-60% with prosthesis
• Wheelchair-Dependent: 20-30%
• Bed-bound: 10-20%

Contralateral Limb:

• Amputation Risk: 10% per year
• Emphasizes: Need for continued cardiovascular risk management in contralateral limb

Cardiovascular Outcomes

PAD patients face high cardiovascular event rates:

MACE (Major Adverse Cardiovascular Events): 5-7% per year

Prognostic Factors

Good Prognosis

• Smoking cessation
• Medication adherence (antiplatelet, statin)
• Successful revascularization with sustained patency
• Single-level disease
• Mild symptoms (long claudication distance)
• Good functional status

Poor Prognosis

• Continued smoking (most powerful negative predictor)
• Diabetes (especially poor control)
• Chronic kidney disease (especially dialysis-dependent)
• Heart failure
• Multi-level arterial disease
• Tissue loss at presentation
• Failed revascularization
• Non-ambulatory status

Quality of Life

Claudication Impact:

• Reduces walking distance and mobility
• Limits employment and recreational activities
• Causes social isolation
• Impairs mental health (anxiety, depression common)

CLTI Impact:

• Severe, constant pain
• Sleep deprivation
• Dependence on caregivers
• Profound reduction in quality of life (worse than many cancers)

Post-Amputation:

• Body image disturbance
• Psychological distress (depression in 30-40%)
• Loss of independence
• Phantom limb pain

Improvement with Treatment:

• Successful revascularization improves quality of life scores significantly
• Supervised exercise improves functional status and psychological well-being
• Pain relief (medical or revascularization) improves sleep and mood

---

10. Evidence & Guidelines

Key Guidelines

ESC/ESVS Guidelines on Peripheral Arterial Diseases (2024) [5]

Recommendations:

• ABPI measurement in all patients with suspected PAD
• Best medical therapy (antiplatelet, statin, ACE-I, smoking cessation) for all PAD patients
• Supervised exercise therapy as first-line for claudication
• Revascularization for CLTI and lifestyle-limiting claudication
• Multidisciplinary team approach for CLTI

NICE NG168: Peripheral Arterial Disease (2020) [6]

Recommendations:

• Offer supervised exercise programs (12 weeks minimum)
• Naftidrofuryl or cilostazol if exercise ineffective
• Consider revascularization for lifestyle-limiting claudication after exercise trial
• Urgent vascular referral for CLTI

AHA/ACC Guideline on Lower Extremity PAD (2016) [25]

Recommendations:

• Antiplatelet therapy for all symptomatic PAD
• Statin therapy regardless of baseline cholesterol
• Smoking cessation counseling and pharmacotherapy
• Structured exercise program or supervised exercise therapy
• Revascularization for CLTI or disabling claudication

Landmark Trials

COMPASS Trial (2017) [18]

Design: RCT of rivaroxaban 2.5mg BD + aspirin vs aspirin alone in stable vascular disease

Population: 7,470 PAD patients (subset of 27,395 total)

Results (PAD subgroup):

• MACE Reduction: 24% (HR 0.76, pless than 0.001)
• Major Adverse Limb Events: 43% reduction (HR 0.57, pless than 0.001)
• Major Bleeding: Increased (HR 1.61) but low absolute rate

Implication: Rivaroxaban + aspirin is an option for high-risk PAD patients; weigh bleeding risk

VOYAGER-PAD Trial (2020) [19]

Design: RCT of rivaroxaban 2.5mg BD + aspirin vs aspirin alone post-revascularization

Population: 6,564 PAD patients after lower extremity revascularization

Results:

• Primary Outcome (ALI, major amputation, MI, stroke, CV death): 15% reduction (HR 0.85, p=0.009)
• Major Adverse Limb Events: 24% reduction
• Major Bleeding: Small increase (TIMI major 2.65% vs 1.87%)

Implication: Consider rivaroxaban + aspirin for 6-12 months post-revascularization

BEST-CLI Trial (2022) [24]

Design: RCT comparing endovascular vs surgical revascularization in CLTI

Population: 1,830 CLTI patients randomized by vein availability

• Cohort 1: Adequate saphenous vein available
• Cohort 2: No adequate vein (prosthetic or endovascular only)

Results:

• Cohort 1: Surgery superior (amputation-free survival, reintervention rates lower)
• Cohort 2: Endovascular preferred (prosthetic bypass had poor outcomes)

Implication: Surgical bypass with vein is preferred for CLTI if patient fit and vein available; endovascular preferred if no vein

Supervised Exercise Meta-Analyses

Cochrane Review (2017) [10]:

• Maximum Walking Distance: Increased by 120-180 meters
• Pain-Free Walking Distance: Increased by 80-100 meters
• Quality of Life: Significant improvement

Implication: Supervised exercise is effective first-line therapy for claudication; comparable to revascularization for walking distance improvement in many patients

Heart Protection Study (Statin Therapy) [20]

Design: RCT of simvastatin 40mg vs placebo in high-risk patients

PAD Subgroup: 6,748 PAD patients

Results:

• Major Vascular Events: 22% reduction (pless than 0.0001)
• All-Cause Mortality: 12% reduction

Implication: High-intensity statin therapy is mandatory in PAD

Emerging Evidence

Gene and Cell Therapy

Concept: Deliver pro-angiogenic factors (VEGF, FGF) or stem/progenitor cells to promote collateral growth

Status: Mixed trial results; some show improved wound healing and amputation reduction, others show no benefit

Limitation: Heterogeneous patient populations, variable delivery methods, lack of standardized protocols

Deep Vein Arterialization (DVA)

Concept: Create arteriovenous connection via tibial veins to perfuse foot via venous system in "no-option" CLTI

Evidence: Emerging case series and registry data show 70-80% limb salvage at 1 year in otherwise non-revascularizable patients

Status: Available in specialized centers; awaiting larger RCTs

---

11. Patient/Layperson Explanation

What is Peripheral Arterial Disease (PAD)?

PAD, also called chronic limb ischaemia, occurs when the arteries in your legs become narrowed or blocked. These arteries are like pipes that carry blood (and oxygen) to your leg muscles. When they get clogged with fatty deposits (the same process that causes heart attacks), your legs don't get enough blood flow.

What Causes PAD?

The main causes are:

• Smoking: The single biggest risk factor
• Diabetes: High blood sugar damages arteries
• High Cholesterol: Causes fatty buildup in arteries
• High Blood Pressure: Damages artery walls
• Getting Older: Arteries naturally stiffen with age

What Are the Symptoms?

Early Stage - Claudication (Leg Cramping):

• Cramping, aching, or tiredness in your calf, thigh, or buttock when you walk
• Happens at about the same distance every time (for example, after walking 200 meters)
• Goes away after resting for 2-3 minutes
• Gets worse over time if not treated

Advanced Stage - Critical Ischaemia:

• Pain in your foot or toes even when resting (often at night)
• Sores or ulcers on your toes or feet that won't heal
• Toes or part of foot turning black (gangrene)
• This is an emergency and requires urgent medical attention

How is PAD Diagnosed?

Ankle-Brachial Pressure Index (ABPI):

• A simple test that compares blood pressure in your ankle to blood pressure in your arm
• Takes about 10-15 minutes
• Uses a blood pressure cuff and a small ultrasound device
• Normal: ABPI 1.0-1.3
• PAD: ABPI less than 0.9
• Severe PAD: ABPI less than 0.4

Other Tests:

• Ultrasound scan to see where blockages are
• CT or MRI scan for detailed pictures of your arteries

How is PAD Treated?

Treatment has two goals:

1. Prevent heart attack and stroke (because PAD means you're at higher risk)
2. Improve leg symptoms and prevent amputation

Medications (Everyone Needs These)

1. Blood Thinner (aspirin or clopidogrel): Prevents clots
2. Cholesterol Medicine (statin): Lowers cholesterol and stabilizes artery plaques
3. Blood Pressure Medicine: Protects arteries and heart

Lifestyle Changes (The Most Important Treatments!)

1. STOP SMOKING:

   • The single most important thing you can do
   • Reduces amputation risk by 50%
   • Quitting is hard, but help is available (nicotine patches, medications, counseling)

2. Exercise Program:

   • Walking is the best medicine for claudication
   • Supervised exercise programs help you walk 3 times per week
   • Start slowly, walk until you feel pain, rest, then repeat
   • Over 3-6 months, you can improve walking distance by 50-200%

3. Healthy Diet:

   • Lots of vegetables and fruits
   • Less saturated fat and salt
   • Helps control cholesterol, blood pressure, and diabetes

4. Control Diabetes (if you have it):

   • Keep blood sugar controlled
   • Check your feet every day for cuts or sores

Procedures (For Severe Cases)

Angioplasty:

• A small balloon is inflated inside your artery to open it up
• Sometimes a metal tube (stent) is left in to keep it open
• Done through a small puncture in your groin
• You're awake (local anesthetic)
• Go home the same day or next day

Bypass Surgery:

• A new "pipe" is created to bypass the blocked artery
• Uses a vein from your leg or a synthetic tube
• Requires general anesthetic
• Hospital stay 5-7 days
• More invasive but longer-lasting than angioplasty

Amputation:

• Only if the leg cannot be saved
• Last resort when blood flow cannot be restored
• Focuses on preserving as much of the leg as possible
• Rehabilitation and prosthetic (artificial leg) fitting helps you walk again

Living with PAD

Daily Foot Care (Especially if You Have Diabetes)

• Inspect your feet daily: Look for cuts, blisters, or red spots
• Wash your feet daily: Dry carefully, especially between toes
• Moisturize: Prevent dry, cracked skin (but not between toes)
• Trim toenails carefully: Straight across; see podiatrist if difficult
• Wear proper shoes: Well-fitting, no tight areas or rubbing
• Never go barefoot: Even indoors
• See a podiatrist: Regular foot care, especially for diabetics

When to See a Doctor Urgently

• Sudden severe leg pain (may indicate acute blockage)
• New sore or ulcer on foot or toes
• Toes turning black or blue
• Pain in foot at rest (especially at night)
• Signs of infection: Redness, warmth, pus, fever

What Can You Expect?

• With treatment: Most people with claudication stay stable or improve over time
• Without smoking cessation and medications: Risk of worsening and amputation
• Critical ischaemia: Requires urgent treatment to save the leg
• Life expectancy: PAD is a sign of widespread artery disease. Managing your heart and stroke risk is just as important as treating your legs.

Key Messages

1. PAD is serious: It's not just a leg problem - it's a sign your arteries are clogged in other places too (heart, brain)
2. Stop smoking: Nothing else comes close to this in importance
3. Take your medications every day: Even if you feel fine
4. Keep walking: It's proven to work
5. Look after your feet: Daily checks and good footwear prevent complications
6. See your doctor regularly: Keep blood pressure, cholesterol, and diabetes under control

---

12. References

Guidelines

1. Song P, Rudan D, Zhu Y, et al. Global, regional, and national prevalence and risk factors for peripheral artery disease in 2015: an updated systematic review and analysis. Lancet Glob Health. 2019;7(8):e1020-e1030. PMID: 31303293

2. Aboyans V, Ricco JB, Bartelink MEL, et al. 2024 ESC/ESVS Guidelines on the Diagnosis and Treatment of Peripheral Arterial Diseases. Eur Heart J. 2024;45(36):3538-3700. (ESC Guidelines 2024)

3. Aboyans V, Criqui MH, Abraham P, et al. Measurement and interpretation of the ankle-brachial index: a scientific statement from the American Heart Association. Circulation. 2012;126(24):2890-2909. PMID: 23159553

4. Criqui MH, Aboyans V. Epidemiology of peripheral artery disease. Circ Res. 2015;116(9):1509-1526. PMID: 25908725

5. Aboyans V, Ricco JB, Bartelink MEL, et al. 2017 ESC Guidelines on the Diagnosis and Treatment of Peripheral Arterial Diseases. Eur Heart J. 2018;39(9):763-816. PMID: 28886620

6. NICE. Peripheral arterial disease: diagnosis and management. Clinical guideline [NG168]. Published August 2020. nice.org.uk/guidance/ng168

7. Conte MS, Bradbury AW, Kolh P, et al. Global vascular guidelines on the management of chronic limb-threatening ischemia. J Vasc Surg. 2019;69(6S):3S-125S. PMID: 30876641

8. Jaff MR, White CJ, Hiatt WR, et al. An Update on Methods for Revascularization and Expansion of the TASC Lesion Classification to Include Below-the-Knee Arteries: A Supplement to the Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). Vasc Med. 2015;20(5):465-478. PMID: 26324624

9. Sigvant B, Lundin F, Walfridsson H. The Risk of Disease Progression in Peripheral Arterial Disease is Higher than Expected: A Meta-Analysis of Mortality and Disease Progression in Peripheral Arterial Disease. Eur J Vasc Endovasc Surg. 2016;51(3):395-403. PMID: 26711791

10. Lane R, Ellis B, Watson L, Leng GC. Exercise for intermittent claudication. Cochrane Database Syst Rev. 2014;(7):CD000990. PMID: 25037027

11. Norgren L, Hiatt WR, Dormandy JA, et al. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). J Vasc Surg. 2007;45 Suppl S:S5-67. PMID: 17223489

12. Jones WS, Patel MR, Dai D, et al. High mortality risks after major lower extremity amputation in Medicare patients with peripheral artery disease. Am Heart J. 2013;165(5):809-815. PMID: 23622919

13. Lo RC, Bensley RP, Dahlberg SE, et al. Presentation, treatment, and outcome differences between men and women undergoing revascularization or amputation for lower extremity peripheral arterial disease. J Vasc Surg. 2014;59(2):409-418. PMID: 24080134

14. Allison MA, Ho E, Denenberg JO, et al. Ethnic-specific prevalence of peripheral arterial disease in the United States. Am J Prev Med. 2007;32(4):328-333. PMID: 17383564

15. American Diabetes Association. Peripheral arterial disease in people with diabetes. Diabetes Care. 2003;26(12):3333-3341. PMID: 14633825

16. Diehm C, Allenberg JR, Pittrow D, et al. Mortality and vascular morbidity in older adults with asymptomatic versus symptomatic peripheral artery disease. Circulation. 2009;120(21):2053-2061. PMID: 19901192

17. Antithrombotic Trialists' Collaboration. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ. 2002;324(7329):71-86. PMID: 11786451

18. Eikelboom JW, Connolly SJ, Bosch J, et al. Rivaroxaban with or without Aspirin in Stable Cardiovascular Disease (COMPASS). N Engl J Med. 2017;377(14):1319-1330. PMID: 28844192

19. Bonaca MP, Bauersachs RM, Anand SS, et al. Rivaroxaban in Peripheral Artery Disease after Revascularization (VOYAGER PAD). N Engl J Med. 2020;382(21):1994-2004. PMID: 32222135

20. Heart Protection Study Collaborative Group. Randomized trial of the effects of cholesterol-lowering with simvastatin on peripheral vascular and other major vascular outcomes in 20,536 people with peripheral arterial disease and other high-risk conditions. J Vasc Surg. 2007;45(4):645-654. PMID: 17398372

21. Zinman B, Wanner C, Lachin JM, et al. Empagliflozin, Cardiovascular Outcomes, and Mortality in Type 2 Diabetes (EMPA-REG OUTCOME). N Engl J Med. 2015;373(22):2117-2128. PMID: 26378978

22. Murphy TP, Cutlip DE, Regensteiner JG, et al. Supervised Exercise, Stent Revascularization, or Medical Therapy for Claudication Due to Aortoiliac Peripheral Artery Disease: The CLEVER Study. J Am Coll Cardiol. 2015;65(10):999-1009. PMID: 25766947

23. Pande RL, Hiatt WR, Zhang P, et al. A pooled analysis of the durability and predictors of treatment response of cilostazol in patients with intermittent claudication. Vasc Med. 2010;15(3):181-188. PMID: 20375125

24. Farber A, Menard MT, Conte MS, et al. Surgery or Endovascular Therapy for Chronic Limb-Threatening Ischemia (BEST-CLI). N Engl J Med. 2022;387(25):2305-2316. PMID: 36475950

25. Gerhard-Herman MD, Gornik HL, Barrett C, et al. 2016 AHA/ACC Guideline on the Management of Patients with Lower Extremity Peripheral Artery Disease. Circulation. 2017;135(12):e726-e779. PMID: 27840333

---