Cardiovascular

Peripheral artery disease: ABI interpretation and medical management

Clinical Overview and When to Suspect PAD

— Exertional calf, thigh, or buttock pain reproducibly relieved by rest (classic intermittent claudication)

— Non-healing foot ulcer, gangrene, or rest pain in a dependent foot

— Diminished or absent pedal pulses on routine exam

— Erectile dysfunction + buttock claudication (Leriche syndrome — aortoiliac disease)

— Atypical leg symptoms in diabetics or CKD patients (neuropathy masks claudication)

— Age ≥65

— Age 50–64 with risk factors (smoking, DM, HLD, HTN, family hx)

— Age <50 with DM and one additional risk factor

— Known atherosclerosis in another vascular bed

— Any patient with exertional leg symptoms or non-healing wound

Board pearl: A patient with diabetes and a non-healing toe ulcer needs an ABI and toe-brachial index (TBI) because medial calcinosis falsely elevates ABI. Don't anchor on "pulses palpable."

Step 3 management: PAD diagnosis is also a mandate to optimize global CV risk — statin, antiplatelet, BP, glycemic control, smoking cessation — not just leg symptoms. Treat the patient, not the limb.

Peripheral artery disease (PAD) = atherosclerotic narrowing of non-coronary, non-cerebral arteries, most often lower extremity. Prevalence rises sharply after age 60; ~12–20% of US adults >60.

Pathophysiology: same atherosclerotic cascade as CAD — endothelial dysfunction, lipid-laden plaque, calcification — driven by smoking, DM, HTN, dyslipidemia, CKD, hyperhomocysteinemia.

PAD is a coronary heart disease risk equivalent: 5-year MI/stroke/vascular death risk ~20%. Most PAD patients die of CV events, not limb loss.

When to suspect:

High-prevalence groups in whom to screen with ABI:

USPSTF: insufficient evidence to screen asymptomatic general population (I statement), but AHA/ACC recommends targeted ABI in the above groups — a frequent Step 3 distinction.

Presentation Patterns and Key History

— Cramping, aching, fatigue in calf (femoropopliteal), thigh (iliac), or buttock (aortoiliac)

— Reproducible at a fixed walking distance, relieved within <10 minutes of rest while standing

— Does not occur at rest, does not require sitting or positional change

— Ischemic rest pain >2 weeks: burning forefoot/toe pain, worse supine, relieved by dangling foot off bed

— Non-healing ulcer (typically lateral malleolus, toe tips, pressure points)

— Gangrene

— Implies multilevel disease; high amputation and mortality risk

— Walking distance to symptom onset, distance to forced stop, recovery time

— Functional impact (occupation, ADLs, stairs)

— Tobacco: pack-years, current vs former, readiness to quit

— DM duration, A1c, prior foot exams

— Wound history: location, duration, prior debridement

— Prior vascular interventions, contralateral limb status

— CV history: angina, prior MI, CVA, AAA screening status (men 65–75 who ever smoked → one-time US)

— Medications: already on statin, antiplatelet, antihypertensives?

Key distinction: Neurogenic claudication (spinal stenosis) — pain relieved by flexion/sitting, not just rest; provoked by standing, not just walking; variable distance threshold. Vascular claudication — relieved by simply stopping (still standing), fixed reproducible distance.

Board pearl: Rest pain that improves by dangling the foot = gravity-dependent perfusion = advanced PAD/CLTI, not neuropathy.

Classic intermittent claudication (only ~10–35% of PAD patients):

Atypical leg symptoms (>50% of PAD): exertional leg discomfort that doesn't fit classic pattern — common in women, elderly, diabetics, sedentary patients.

Chronic limb-threatening ischemia (CLTI) — formerly "critical limb ischemia":

Acute limb ischemia (ALI) — sudden onset (<2 weeks): the 6 Ps — Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia. Surgical emergency.

Key history elements to capture for Step 3:

Physical Exam Findings and Hemodynamic Assessment

— Hair loss over dorsum of foot and shins, shiny atrophic skin, thickened brittle nails

— Dependent rubor with elevation pallor (Buerger test): elevate leg 60° for 1 min → pallor; dangle → reactive hyperemia >20 sec

— Ulcers: arterial ulcers are distal, punched-out, painful, dry, on toes/lateral malleolus/pressure points; venous ulcers are medial malleolus, weepy, irregular borders, less painful

— Muscle atrophy in advanced disease

— Pulses: femoral, popliteal, dorsalis pedis, posterior tibial — graded 0 (absent), 1+ (diminished), 2+ (normal), 3+ (bounding/aneurysmal)

— Cool skin temperature, prolonged capillary refill (>3 sec)

— Abdominal palpation for pulsatile mass (AAA association)

— Patient supine 10 min, Doppler probe

— Measure systolic BP in both brachial arteries (use higher)

— Measure systolic BP in dorsalis pedis and posterior tibial of each ankle (use higher of the two per leg)

— ABI per leg = higher ankle pressure / higher brachial pressure

— >1.40: non-compressible/calcified vessels (DM, CKD, elderly) → get TBI

— 1.00–1.40: normal

— 0.91–0.99: borderline → consider exercise ABI

— 0.70–0.90: mild PAD

— 0.40–0.69: moderate PAD

— <0.40: severe PAD, often CLTI territory

Step 3 management: A diabetic with classic claudication but ABI of 1.32 — do not rule out PAD. Order TBI and/or duplex; calcified tibials mask disease.

Board pearl: Resting ABI 0.95 + reproducible claudication → exercise ABI is the next best test.

Inspection:

Palpation:

Auscultation: femoral, iliac, abdominal aortic bruits.

Ankle-Brachial Index (ABI) — bedside hemodynamic gold standard:

ABI interpretation:

Toe-Brachial Index (TBI): <0.70 = abnormal; digital vessels rarely calcify.

Exercise ABI: drop >20% from baseline, or absolute ankle pressure drop >30 mmHg, confirms PAD when resting ABI is borderline.

Diagnostic Workup — Initial Labs and Studies

— Lipid panel (fasting or non-fasting per ACC/AHA)

— HbA1c and fasting glucose — screen for DM if not known

— Basic metabolic panel: creatinine/eGFR (statin and contrast dosing; metformin/SGLT2 decisions)

— CBC (anemia worsens claudication; baseline before antiplatelet)

— Lipoprotein(a) once in lifetime — emerging ACC recommendation, especially with premature PAD or family hx

— Hs-CRP if risk stratification borderline

— Consider hypercoagulable workup (factor V Leiden, antiphospholipid, homocysteine) only if PAD in patient <50, no traditional risk factors, or recurrent thrombosis

— TSH if symptoms suggest, but not routine

— Cuffs at thigh, calf, ankle, metatarsal; pressure drop >20 mmHg between adjacent segments localizes lesion

— High thigh < brachial → aortoiliac disease

— Thigh–calf drop → femoropopliteal

— Calf–ankle drop → infrapopliteal/tibial

— Wound cultures only if clinical infection signs (purulence, surrounding cellulitis, systemic signs) — colonization vs infection distinction

— Plain films of foot if osteomyelitis suspected; MRI is more sensitive

— Probe-to-bone test: positive → high PPV for osteomyelitis in diabetic foot

CCS pearl: In a CCS PAD case, on Day 1 order: ABI with segmental pressures, lipid panel, HbA1c, BMP, CBC, ECG, and counsel smoking cessation + start statin + aspirin or clopidogrel. Don't jump to angiography.

Board pearl: Routine thrombophilia workup in typical older smoker with PAD is low-yield and not indicated.

First-line confirmatory test for suspected PAD = resting ABI with segmental pressures if symptomatic. No imaging needed before ABI in most outpatient scenarios.

Labs to obtain at PAD diagnosis (global CV risk + procedural prep):

Segmental limb pressures and pulse volume recordings (PVR):

ECG: baseline for CV risk and pre-procedural; many PAD patients have silent CAD.

Resting ABI alone suffices for diagnosis and medical management decisions. Advanced imaging is reserved for revascularization planning.

Wound workup (if ulcer present):

Diagnostic Workup — Advanced and Confirmatory Imaging

— First-line anatomic imaging in most centers

— No contrast, no radiation; operator-dependent

— Identifies stenosis location and severity (peak systolic velocity ratio >2.0 = ≥50% stenosis)

— Good for follow-up after bypass/stent

— Fast, widely available, excellent for aortoiliac and infrainguinal mapping

— Drawbacks: iodinated contrast (CKD, contrast-associated AKI risk), radiation, calcium blooming artifact in heavily calcified tibials

— Pre-procedure: hold metformin if eGFR <30 or per institutional protocol; hydrate

— No iodinated contrast; uses gadolinium

— Avoid gadolinium if eGFR <30 (nephrogenic systemic fibrosis risk — though newer macrocyclic agents are lower risk)

— Tends to overestimate stenosis; metallic stents create artifact

— Historic gold standard; now reserved for cases proceeding to simultaneous endovascular intervention

— Highest spatial resolution; allows pressure gradients across lesions

— Risks: contrast nephropathy, access-site hematoma, atheroembolism, dissection

— CTA is the test of choice for rapid anatomic delineation if hemodynamically stable

— Echo + ECG to identify cardioembolic source (AF, LV thrombus, endocarditis)

— Labs: CK, lactate, K+ (rhabdomyolysis/reperfusion), type & screen, coags

Key distinction: Duplex is the screening anatomic test; CTA/MRA for procedural planning; DSA when you intend to fix it in the same visit. Don't order CTA just to "confirm" PAD already diagnosed by ABI.

Board pearl: eGFR 22 patient needing pre-revascularization imaging → duplex first, then consider CO₂ angiography or limited DSA with iso-osmolar contrast to minimize nephrotoxicity.

Advanced imaging is indicated only when revascularization is being planned (lifestyle-limiting claudication failing medical therapy, CLTI, ALI) — not for diagnosis confirmation alone.

Arterial duplex ultrasound:

CT angiography (CTA):

MR angiography (MRA):

Digital subtraction angiography (DSA) — catheter-based:

Acute limb ischemia workup:

Risk Stratification and First-Line Management Logic

— Fontaine: I asymptomatic, IIa mild claudication, IIb moderate-severe claudication, III rest pain, IV ulcer/gangrene

— Rutherford: 0 asymptomatic → 6 major tissue loss

— WIfI (Wound, Ischemia, foot Infection): risk-stratifies amputation and benefit of revascularization in CLTI

— GLASS (Global Limb Anatomic Staging System): anatomic complexity for revascularization planning

— Asymptomatic PAD (ABI ≤0.90): aggressive CV risk reduction only — statin, antiplatelet if very low ABI or polyvascular disease, BP/glucose control, smoking cessation. No revascularization.

— Stable claudication: supervised exercise therapy (SET) + structured medical therapy for ≥3 months before considering revascularization

— Lifestyle-limiting claudication despite optimal medical therapy + SET: shared decision-making for endovascular or surgical revascularization

— CLTI: prompt vascular surgery referral; revascularization to preserve limb; multidisciplinary "toe and flow" team (vascular + podiatry + ID + endocrine + wound care)

— ALI: emergent anticoagulation + vascular surgery; thrombolysis vs thrombectomy vs surgical embolectomy based on Rutherford acute ischemia class

— Antiplatelet

— Blood pressure <130/80 (ACC/AHA); ACEi/ARB preferred

— Cholesterol: high-intensity statin, LDL goal <70 mg/dL (ACC 2018; some advocate <55)

— Diabetes: A1c individualized (~7%); prefer SGLT2 inhibitors and GLP-1 RAs for CV benefit

— Exercise + smoking cEssation

— Foot care, Flu/COVID/pneumococcal vaccines

Step 3 management: A patient with stable claudication walking 2 blocks asking about a stent — answer is structured exercise + statin + antiplatelet + cilostazol for 3 months first, not immediate angiography.

Board pearl: Smoking cessation is the single most impactful intervention — reduces progression to CLTI, amputation, MI, and death.

Classification systems Step 3 expects you to recognize:

Treatment hierarchy based on category:

Foundational interventions for every PAD patient (the "ABCDEs"):

Pharmacotherapy — First-Line Drug Regimen

— Clopidogrel 75 mg daily is preferred monotherapy in many guidelines (CAPRIE trial showed modest benefit over ASA in PAD subgroup)

— Aspirin 75–100 mg daily acceptable alternative

— Dual antiplatelet therapy (DAPT) routinely is not recommended; reserved for ~1–6 months post-endovascular intervention

— Low-dose rivaroxaban 2.5 mg BID + aspirin 81 mg (COMPASS, VOYAGER PAD): reduces MACE and MALE in symptomatic PAD and post-revascularization; bleeding risk must be weighed

— High-intensity statin (atorvastatin 40–80 mg or rosuvastatin 20–40 mg)

— LDL goal <70 mg/dL (ACC/AHA 2018 secondary prevention)

— Add ezetimibe if not at goal; then consider PCSK9 inhibitor (alirocumab, evolocumab) or inclisiran

— Statins independently improve walking distance and reduce limb events

— Target <130/80 mmHg

— ACEi/ARB first-line (ramipril shown to reduce CV events in HOPE trial)

— β-blockers are safe in PAD — old dogma that they worsen claudication is largely debunked; use when otherwise indicated (post-MI, HFrEF)

— A1c ~7% individualized

— Prefer SGLT2 inhibitors (empagliflozin, dapagliflozin) and GLP-1 RAs (semaglutide, liraglutide) for proven CV and renal benefit

— Canagliflozin carries an FDA warning for increased amputation risk in PAD — choose alternative SGLT2i in PAD patients

— Phosphodiesterase-3 inhibitor; vasodilator + antiplatelet

— Improves pain-free walking distance by ~50%

— Contraindicated in heart failure of any severity (PDE3 inhibitors ↑ mortality in HF)

— Side effects: headache, palpitations, diarrhea; trial for 3 months

Board pearl: PAD patient with HFrEF and claudication wanting symptom relief → cilostazol is contraindicated. Optimize SET, statin, antiplatelet, and consider rivaroxaban 2.5 mg BID + ASA.

Antiplatelet therapy (all symptomatic PAD; consider in asymptomatic with ABI ≤0.90):

Statin therapy — mandatory:

Antihypertensives:

Diabetes management:

Cilostazol 100 mg BID — symptom-directed for claudication:

Pentoxifylline — minimal benefit, generally not recommended.

Revascularization and Procedural Management

— Lifestyle-limiting claudication refractory to ≥3 months optimal medical therapy + supervised exercise

— Chronic limb-threatening ischemia (rest pain, non-healing ulcer, gangrene)

— Acute limb ischemia

— Balloon angioplasty ± stenting (bare-metal, drug-eluting, drug-coated balloons)

— Atherectomy for calcified lesions

— Preferred for focal aortoiliac and femoropopliteal disease, shorter lesions, higher surgical risk patients

— Post-procedure: DAPT (ASA + clopidogrel) for 1–6 months, then single antiplatelet ± low-dose rivaroxaban

— Lower morbidity, shorter hospitalization; higher restenosis vs surgery

— Preferred for long-segment occlusions, infrainguinal CLTI with good autogenous vein, younger lower-risk patients (BEST-CLI trial: surgical bypass with adequate saphenous vein superior to endovascular for CLTI)

— Aortobifemoral bypass for aortoiliac; fem-pop or fem-tibial bypass for infrainguinal

— Autogenous greater saphenous vein > prosthetic graft for below-knee

— Post-op: lifelong antiplatelet; consider rivaroxaban 2.5 mg BID + ASA (VOYAGER)

— Immediate IV unfractionated heparin bolus + infusion (goal aPTT 2× control)

— Pain control, keep limb in dependent position, no warming/cooling extremes

— Vascular surgery emergent consult

— Rutherford class: I (viable) → urgent imaging + revascularization; IIa (marginally threatened) → urgent revascularization; IIb (immediately threatened) → emergent revascularization (catheter-directed thrombolysis or surgical thrombectomy); III (irreversible) → primary amputation

— Monitor for reperfusion syndrome: hyperkalemia, acidosis, myoglobinuria, compartment syndrome — fasciotomy if compartment pressures rise

CCS pearl: ALI case — order heparin bolus immediately, then CTA, then vascular surgery consult. Don't waste time on duplex first if surgery is imminent.

Step 3 management: Post-endovascular PAD patient — DAPT 1–6 months, lifelong single antiplatelet + statin, surveillance duplex at 1, 3, 6, 12 months, then annually.

Indications for revascularization:

Endovascular (percutaneous) therapy:

Surgical bypass:

Acute limb ischemia management (CCS-relevant):

Special Populations — Elderly and Renal/Hepatic Impairment

— High PAD prevalence (>20%); often atypical or silent due to limited ambulation, neuropathy, dementia

— Screen with ABI in any age >65, or with foot wound/exam findings

— Polypharmacy and falls: aggressive BP lowering can cause orthostasis and falls; individualize SBP target (130–140 if frailty)

— Statins: continue in secondary prevention regardless of age; deprescribe only with limited life expectancy (<1 year) or intolerance

— Bleeding risk on DAPT or rivaroxaban + ASA — weigh ischemic vs hemorrhagic benefit (use HAS-BLED concepts, frailty index)

— Functional assessment before revascularization: a non-ambulatory nursing home patient with rest pain may benefit from palliative amputation rather than complex bypass

— PAD and CKD are bidirectional risk multipliers; amputation risk markedly elevated

— ABI can be falsely elevated (medial calcinosis) — use TBI

— Contrast considerations:

— eGFR <30: minimize iodinated contrast; use CO₂ angiography, isosmolar contrast, or duplex-only planning

— Pre-/post-hydration with isotonic saline; NAC and bicarbonate are no longer recommended (PRESERVE trial)

— Gadolinium <30 eGFR: avoid older linear agents (NSF risk); newer macrocyclic agents acceptable in shared decision

— Statin dosing: rosuvastatin max 10 mg/day if eGFR <30; atorvastatin no renal dose adjustment

— Metformin: hold pre-contrast if eGFR 30–60 per protocol; contraindicated <30

— SGLT2 inhibitors: most approved down to eGFR 20–25; avoid canagliflozin in PAD

— Statins: avoid in active decompensated cirrhosis or unexplained transaminitis >3× ULN; otherwise compensated cirrhosis tolerates statins

— Cilostazol: hepatic metabolism — caution; avoid with strong CYP3A4 inhibitors

— Clopidogrel: prodrug requiring CYP2C19 activation — reduced efficacy in poor metabolizers; consider ticagrelor or aspirin alternative

Board pearl: Diabetic CKD patient with foot ulcer and ABI 1.45 — calcified vessels masking disease. Get TBI, refer to multidisciplinary limb-preservation team.

Step 3 management: Don't withhold statin from a healthy 85-year-old with PAD purely because of age — secondary prevention benefit persists.

Elderly (≥75):

Chronic kidney disease:

Hepatic impairment:

Special Populations — Pregnancy, Premature PAD, and Other Subgroups

— Takayasu arteritis: large-vessel vasculitis in young women (especially Asian descent); presents with claudication, BP discrepancy between arms, bruits, absent pulses

— Fibromuscular dysplasia (FMD): "string of beads" on angiography; renal arteries most common but iliac/femoral involvement possible

— Antiphospholipid syndrome: arterial thrombosis + pregnancy loss

— Management in pregnancy:

— Aspirin 81 mg is safe and often beneficial

— Statins are contraindicated (category X historically; recent FDA softening but still generally avoided)

— ACEi/ARBs contraindicated — use labetalol, nifedipine, methyldopa

— Warfarin contraindicated in 1st trimester (embryopathy) and near delivery; LMWH preferred if anticoagulation needed

— Rivaroxaban not recommended

— Workup beyond standard atherosclerotic risk factors:

— Homocysteine, lipoprotein(a)

— Hypercoagulable panel (factor V Leiden, prothrombin gene, antiphospholipid, protein C/S, antithrombin)

— Vasculitis screen if systemic features (ESR/CRP, ANCA, autoimmune panel)

— Consider thromboangiitis obliterans (Buerger disease): male smokers <45, distal arteries and veins, corkscrew collaterals on angiography; smoking cessation is the only effective therapy

— Cocaine and amphetamine use → vasospastic and accelerated atherosclerosis

— More likely to present atypically, with non-classic leg symptoms or asymptomatic functional decline

— Under-diagnosed and under-treated; ensure ABI screening in appropriate age/risk groups

— Higher peri-procedural complication rates with endovascular intervention

Board pearl: Young male smoker with distal digital ischemia, migratory superficial phlebitis, and angiography showing corkscrew collaterals = Buerger disease. Cure = complete tobacco cessation — nothing else works.

Key distinction: Takayasu (young women, large vessels, upper extremity claudication, BP asymmetry) vs giant cell arteritis (>50, temporal, jaw claudication) vs Buerger (young male smokers, small distal vessels).

PAD in pregnancy — rare (atherosclerotic PAD is uncommon in childbearing age), but consider:

Premature PAD (<50 years):

Women:

African American patients: higher PAD prevalence and amputation rates; ensure equitable screening and revascularization access.

Complications and Adverse Outcomes

— Progression from claudication to CLTI (~1–2%/year; higher with DM, smoking, low ABI)

— Non-healing ulcer → osteomyelitis → amputation

— Major amputation rate: ~1–4%/year in CLTI; higher in diabetics

— Failed revascularization: restenosis, graft thrombosis, distal embolization

— Reperfusion injury: rhabdomyolysis, hyperkalemia, compartment syndrome

— Wound dehiscence, surgical site infection, lymphocele post-bypass

— Pseudoaneurysm and AV fistula at access site post-endovascular

— MI: 20–30% within 5 years

— Stroke: ~5–10% within 5 years

— All-cause mortality: ~30% at 5 years in symptomatic PAD; >50% at 5 years in CLTI

— PAD patients more likely to die of CAD than lose a limb

— Increased incidence of AAA — screen men 65–75 who ever smoked with one-time abdominal US

— Renal artery stenosis frequently coexists — consider if resistant HTN or rising creatinine on ACEi

— Compartment syndrome — measure pressures, fasciotomy if >30 mmHg or clinical signs (pain out of proportion, paresthesia, paralysis, tense compartments)

— Rhabdomyolysis with hyperkalemia and AKI — aggressive IV fluids, monitor CK, K+, urine output

— Limb loss

— Charcot arthropathy

— Polymicrobial deep infection, gas gangrene, necrotizing fasciitis

— Osteomyelitis under non-healing ulcers — probe-to-bone and MRI

— Statin myopathy, hepatotoxicity

— Cilostazol-induced HF decompensation

— Bleeding from antiplatelet ± low-dose rivaroxaban

— Contrast nephropathy

Board pearl: A PAD patient's leading cause of death is myocardial infarction, not limb loss. Manage like a CAD-equivalent.

Step 3 management: Post-revascularization patient with new fever, calf pain, and rising CK → think reperfusion injury and compartment syndrome — emergent fasciotomy assessment.

Limb complications:

Systemic cardiovascular complications (the dominant mortality driver):

Acute limb ischemia complications:

Diabetic foot complications (PAD + neuropathy synergy):

Medication-related:

When to Escalate Care — Triage, Consult, and Admission

— Stable claudication, no ulcer, no rest pain

— Initiate medical therapy + structured exercise; refer to supervised exercise therapy program (Medicare covers SET for symptomatic PAD since 2017 — 36 sessions over 12 weeks)

— Routine vascular surgery referral for lifestyle-limiting symptoms after 3-month medical trial

— Podiatry referral for diabetic foot care, custom shoes

— Wound care clinic for any non-healing lesion

— New rest pain

— Non-healing or worsening ulcer

— Tissue loss/gangrene without systemic infection

— Rapid functional decline

— ABI <0.4 or TBI <0.4 with symptoms

— Acute limb ischemia (6 Ps) — emergent vascular surgery consult, IV heparin

— Wet gangrene or systemic signs of infection (fever, leukocytosis, sepsis) — IV antibiotics, surgical debridement, possible urgent amputation

— Diabetic foot infection with deep involvement, abscess, or sepsis — IDSA severe classification → inpatient IV antibiotics + surgical eval

— Suspected compartment syndrome post-revascularization

— Hemodynamic instability, AKI, hyperkalemia from reperfusion

— Septic shock from limb infection

— Post-operative hemodynamic monitoring after complex revascularization

— Massive rhabdomyolysis with AKI requiring CRRT

— Concurrent acute MI/stroke

— Vascular surgery (anchor)

— Interventional radiology/cardiology (endovascular)

— Podiatry (offloading, debridement, partial amputations)

— Infectious disease (osteomyelitis, MDR organisms)

— Endocrinology (glycemic control)

— Wound care nursing

— Pain management (rest pain, post-amputation)

— Smoking cessation counseling, behavioral health

CCS pearl: ED PAD case with cold, mottled, pulseless, paralyzed leg — order CBC, BMP, CK, lactate, type & screen, coags, ECG, IV heparin bolus + drip, NPO, vascular surgery STAT, CTA lower extremities. Move the clock fast.

Step 3 management: Limb-threatening ischemia warrants admission, not "follow up in clinic in 2 weeks."

Outpatient management (most PAD patients):

Urgent vascular surgery referral (within days to 1–2 weeks):

Emergency department / inpatient admission:

ICU admission:

Multidisciplinary consults:

Key Differentials — Same-Category (Vascular) Causes

— Sudden onset in patient with AF, recent MI with LV thrombus, endocarditis, prosthetic valve, aortic atheroma

— Often no prior claudication, contralateral pulses normal — distinguishing feature

— Pain at site of embolic lodgment (commonly femoral bifurcation, popliteal trifurcation)

— Workup: ECG (AF), echo (LV thrombus, vegetations), CTA

— Occurs in pre-existing atherosclerotic vessel, often with history of claudication

— Better-developed collaterals → presentation slightly less dramatic than embolic

— Hypercoagulable trigger (dehydration, malignancy, HIT)

— Tearing chest/back pain + cold pulseless extremity

— BP differential between arms

— CTA aorta diagnostic; emergent surgery

— Often bilateral; associated with AAA

— Palpable pulsatile popliteal mass; duplex confirms

— Young athletic male, exercise-induced calf claudication, normal resting pulses

— Pulses diminish with active plantar flexion against resistance

— Diagnosis: provocative duplex or MRA in neutral and stressed positions

— Young patient with claudication, mucinous cyst in popliteal artery adventitia

— MRI shows cyst; resection curative

— Young male smoker, distal small/medium artery and vein involvement

— Corkscrew collaterals on angiography

— Migratory superficial thrombophlebitis

— Smoking cessation is the only proven therapy

— Takayasu (young women, large vessels), GCA (>50, temporal/large vessel), polyarteritis nodosa (medium vessels, mesenteric/renal)

— Elevated ESR/CRP, systemic symptoms

— Young to middle-aged women; "string of beads"; renal > carotid > iliac

— Blue toe syndrome with palpable pulses, livedo reticularis, eosinophilia, AKI — often after catheterization or anticoagulation

Key distinction: Embolic ALI: sudden, no prior claudication, AF/cardiac source, contralateral pulses normal. Thrombotic ALI: prior claudication, atherosclerotic risk factors, contralateral disease often present. Treatment principles differ — embolectomy vs revascularization of underlying lesion.

Acute embolic limb ischemia:

Acute thrombotic limb ischemia:

Aortic dissection with limb malperfusion:

Popliteal artery aneurysm with thrombosis or distal embolization:

Popliteal entrapment syndrome:

Cystic adventitial disease:

Thromboangiitis obliterans (Buerger disease):

Vasculitis:

Fibromuscular dysplasia:

Atheroembolism (cholesterol crystal embolism):

Key Differentials — Other-Category Causes of Leg Pain

— Pain in back, buttocks, thighs with standing and walking

— Relieved by flexion (sitting, leaning on shopping cart), not just stopping

— Variable walking distance day-to-day

— Normal pulses, normal ABI

— MRI lumbar spine diagnostic

— Dermatomal pain, often shooting, with positive straight leg raise

— Not exertionally reproducible in a fixed-distance pattern

— Sensory/motor deficits in nerve root distribution

— Post-DVT iliofemoral obstruction

— "Bursting" pain with exercise, relieved by leg elevation (opposite of arterial!)

— Swelling, varicosities, skin changes (lipodermatosclerosis, hemosiderin staining)

— Venous duplex; ABI normal

— Medial malleolar ulcer, weepy, irregular borders, less painful than arterial

— Treatment: compression therapy (only after confirming ABI >0.8 — never compress an ischemic limb)

— Unilateral swelling, calf tenderness, warmth

— D-dimer, duplex

— Distinct from PAD but can coexist

— Osteoarthritis of hip/knee — pain with weight-bearing, eased by rest, not fixed-distance

— Baker cyst, plantar fasciitis, tendinopathy

— Stress fracture in athletes

— Burning, tingling, "stocking-glove" distribution

— Worse at rest and at night, not exertionally

— Monofilament and vibration testing abnormal

— Often coexists with PAD — both contribute to foot ulcers

— Evening/nighttime symptoms with urge to move; relieved by movement

— Iron studies, ferritin

— Young athletes; pain with prolonged exertion, resolves slowly with rest

— Diagnosis: post-exercise compartment pressures

Key distinction: Relief pattern is the highest-yield differentiator — arterial claudication relieved by stopping (still standing), neurogenic relieved by flexion/sitting, venous relieved by leg elevation.

Board pearl: Patient with leg ulcer — always check ABI before applying compression. ABI <0.8 = do not compress (ischemic limb).

Neurogenic claudication (lumbar spinal stenosis):

Lumbosacral radiculopathy:

Venous claudication:

Chronic venous insufficiency / venous ulcers:

Deep vein thrombosis:

Musculoskeletal:

Diabetic peripheral neuropathy:

Restless legs syndrome:

Compartment syndrome (chronic exertional):

Cellulitis, erysipelas: erythema, warmth, fever — inflammatory, not exertional

Secondary Prevention and Discharge Medications

— Antiplatelet: clopidogrel 75 mg daily or aspirin 81 mg daily

— Post-endovascular intervention: DAPT (ASA + clopidogrel) for 1–6 months, then single agent

— Consider adding rivaroxaban 2.5 mg BID to ASA in symptomatic PAD or post-revascularization (COMPASS/VOYAGER) — balance bleeding risk

— High-intensity statin: atorvastatin 40–80 mg or rosuvastatin 20–40 mg

— LDL goal <70 mg/dL; many advocate <55 in very high risk

— Add ezetimibe, then PCSK9i or inclisiran, if not at goal

— Check lipid panel 4–12 weeks after initiation/change, then annually

— ACEi or ARB: ramipril, lisinopril, losartan — BP <130/80, also reduce CV events independent of BP

— β-blocker: when indicated for CAD/HFrEF — not contraindicated in PAD

— Optimal diabetes regimen (if DM): A1c individualized ~7%

— Metformin first-line

— Add SGLT2 inhibitor (not canagliflozin) and/or GLP-1 RA for CV/renal benefit

— Avoid hypoglycemia (falls, ulcers)

— Cilostazol 100 mg BID if symptomatic claudication and no HF — trial 3 months

— Smoking cessation pharmacotherapy: varenicline (most effective), nicotine replacement, bupropion — combine with behavioral support

— Annual influenza

— Pneumococcal (PCV20 or PCV15 + PPSV23) per age/risk

— COVID-19 boosters per current schedule

— Tdap, zoster (≥50), RSV (≥60)

— Daily foot inspection with mirror or family member

— Properly fitted shoes; never barefoot

— Nail care by podiatrist if neuropathy or vision impairment

— Moisturize but not between toes

— Immediate evaluation of any new wound, blister, or color change

Step 3 management: PAD discharge med rec checklist — statin, antiplatelet (± rivaroxaban 2.5 BID), ACEi/ARB, SGLT2i/GLP-1 if DM, cilostazol if claudication and no HF, smoking cessation, foot care plan, vaccines, AAA screen.

Board pearl: Statin is non-negotiable in PAD regardless of baseline LDL — it's about plaque stabilization and event reduction, not just LDL.

Lifelong medication bundle for symptomatic PAD or asymptomatic with ABI ≤0.90:

Vaccinations:

Foot care education (especially diabetics):

AAA screening: one-time abdominal US in men 65–75 who ever smoked.

Follow-Up, Monitoring, and Rehabilitation

— Stable medically managed PAD: every 3–6 months initially, then annually once stable

— Post-endovascular intervention: 1, 3, 6, 12 months, then annually — clinical exam + duplex surveillance

— Post-bypass graft: similar surveillance with duplex of graft to detect stenosis before occlusion (vein grafts particularly)

— CLTI/non-healing wound: weekly to biweekly wound care visits

— Walking distance, symptom severity, functional status

— Foot inspection (every visit in diabetics)

— Pulses, ABI annually if change in symptoms

— Medication adherence and side effects

— BP, weight, smoking status, A1c, lipid panel

— Renal function (statin, ACEi, SGLT2i)

— First-line for claudication, before revascularization

— Medicare-covered: up to 36 sessions over 12 weeks (extendable to 72)

— Treadmill walking to near-maximal pain (3–5/10), rest, repeat, for 30–60 minutes, 3×/week

— Improves pain-free and maximal walking distance by 50–200%

— Home-based structured programs are an acceptable alternative when SET unavailable

— 5 A's: Ask, Advise, Assess, Assist, Arrange

— Pharmacotherapy + behavioral counseling; combination is most effective

— Set quit date, follow-up call within 1 week

— Moist wound healing principles, debridement, offloading (total contact casts for plantar ulcers)

— Negative pressure wound therapy in select cases

— Hyperbaric oxygen for select Wagner 3 diabetic foot ulcers

— Screen for depression (PHQ-9) — common in chronic pain and limb threat

— Quality of life questionnaires (WIQ, VascuQOL)

Step 3 management: Newly diagnosed claudication patient — start statin + antiplatelet, refer to SET, smoking cessation pharmacotherapy, follow up in 3 months. If lifestyle-limiting after 3 months of adherent therapy → vascular surgery referral for shared decision-making on revascularization.

Board pearl: Supervised exercise therapy outperforms angioplasty for walking distance and durability in stable claudication (CLEVER trial).

Routine follow-up cadence:

At each visit assess:

Supervised Exercise Therapy (SET):

Smoking cessation — at every visit:

Cardiac rehab indications overlap when PAD coexists with recent MI, CABG, PCI, or HF.

Wound care:

Psychosocial:

Ethical, Legal, and Patient Safety Considerations

— Lifestyle-limiting claudication is quality-of-life-driven, not life-saving — patient values dominate

— Discuss realistic outcomes: ~50–80% symptom improvement, restenosis risk, need for repeat procedures

— Surgical alternatives (bypass) vs endovascular — durability vs invasiveness tradeoff

— In CLTI: discuss limb salvage vs primary amputation when functional status, comorbidities, and ambulatory potential favor amputation (e.g., bedbound demented patient)

— Document informed consent including alternatives, risks, benefits, and "doing nothing" option

— Frail elderly patient with non-reconstructable disease and severe comorbidity → palliative wound care, pain control, hospice referral may be most appropriate

— Involve palliative care early; opioids for ischemic rest pain are humane and appropriate

— Respect patient preference against amputation even when surgically indicated — capacity assessment, second opinion if uncertain

— Discharge after revascularization: ensure antiplatelet/anticoagulant prescriptions filled before discharge, written wound care instructions, scheduled follow-up within 1–2 weeks, surveillance duplex scheduled

— Medication reconciliation: DAPT duration, statin, anticoagulation, diabetes meds (hold canagliflozin if PAD)

— Communication to PCP — verbal handoff for unstable wounds or new anticoagulation

— Wrong-site surgery prevention — preoperative time-out, mark surgical limb

— Falls risk in elderly post-revascularization — PT eval before discharge

— Anticoagulation/antiplatelet bleeding risk — review with patient, MedicAlert bracelet

— Compression stockings only after ABI confirmation >0.8 — applying compression to ischemic limb can cause necrosis (sentinel event)

— Black, Hispanic, and rural patients have higher amputation rates for the same disease severity — reflects disparities in revascularization access. Advocate for timely referral.

— Medicare/Medicaid coverage of SET, prosthetics, wound care varies — engage social work early

— Driving restrictions after amputation; report per state DMV requirements

— Workplace disability documentation for FMLA

Step 3 management: Before applying compression bandage to a "venous ulcer" — always document ABI/TBI. Skipping this step in a patient with mixed disease is a classic safety event.

Board pearl: Refusing amputation in capacitated terminal-stage CLTI is the patient's right; pivot to palliative pain management and hospice.

Shared decision-making for revascularization:

Goals of care in advanced CLTI:

Transitions of care — high-risk PAD scenarios:

Patient safety:

Health equity and access:

Mandatory considerations:

High-Yield Associations and Rapid-Fire Facts

— ≤0.90 = PAD; <0.40 = severe/CLTI; >1.40 = non-compressible → TBI

Board pearl: If a question stem mentions a diabetic with foot ulcer and "normal" ABI of 1.3+, the answer is toe-brachial index — they're testing your recognition of medial calcinosis.

Step 3 management: Memorize the bundle — antiplatelet + high-intensity statin + ACEi/ARB + SGLT2i/GLP-1 if DM + smoking cessation + SET + foot care.

ABI cutoffs memorized:

TBI <0.70 = abnormal; gold standard in calcified vessels.

CAPRIE trial: clopidogrel modestly better than ASA in PAD subgroup.

COMPASS / VOYAGER PAD: rivaroxaban 2.5 mg BID + ASA reduces MACE and MALE; consider in symptomatic PAD or post-revascularization.

BEST-CLI: surgical bypass with adequate saphenous vein superior to endovascular for CLTI in good surgical candidates.

CLEVER: SET ≥ angioplasty for walking distance in claudication.

Cilostazol: improves walking ~50%; contraindicated in HF (any severity).

Canagliflozin: ↑ amputation risk in PAD — choose alternative SGLT2i.

Leriche syndrome: aortoiliac disease → buttock claudication + erectile dysfunction + diminished femoral pulses.

Buerger disease (thromboangiitis obliterans): young male smokers, distal arteries + veins, corkscrew collaterals, only treatment = smoking cessation.

Blue toe syndrome with palpable pulses + eosinophilia + AKI post-cath = cholesterol/atheroembolism.

Takayasu: young Asian women, large vessels, BP discrepancy.

FMD: young women, "string of beads," renal > carotid.

AAA screening: one-time US in men 65–75 who ever smoked (USPSTF B).

Arterial ulcers: distal, punched-out, painful, dry, on toes/lateral malleolus.

Venous ulcers: medial malleolus, weepy, irregular, less painful.

Buerger test: elevation pallor + dependent rubor = severe PAD.

Rest pain relieved by dangling foot = advanced PAD/CLTI.

Reperfusion syndrome after revascularization: hyperkalemia, acidosis, myoglobinuria, compartment syndrome.

6 Ps of acute limb ischemia: Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia.

β-blockers are safe in PAD — old contraindication myth.

Statin LDL goal: <70 mg/dL in PAD; many push <55.

BP goal: <130/80; ACEi/ARB first-line.

DAPT post-endovascular: 1–6 months, then single agent.

Medicare SET coverage: 36 sessions over 12 weeks for symptomatic PAD (since 2017).

Pregnancy: avoid statins, ACEi/ARB, warfarin; ASA and LMWH OK.

Probe-to-bone positive + diabetic foot ulcer = high PPV for osteomyelitis.

Board Question Stem Patterns

— Answer: Resting ABI with segmental pressures. Then statin + antiplatelet + SET. Not immediate angiography.

— Answer: Toe-brachial index (TBI) — vessels are calcified/non-compressible.

— Answer: IV heparin bolus + infusion, emergent vascular surgery consult, CTA. Source is likely cardioembolic.

— Answer: Lumbar spinal stenosis — MRI lumbar spine, not ABI as primary.

— Answer: Avoid cilostazol — PDE3 inhibitors increase mortality in HF. Maximize SET + statin + antiplatelet; consider rivaroxaban 2.5 BID + ASA.

— Answer: Complete smoking cessation — only effective therapy.

— Answer: High-intensity statin (atorvastatin 40–80 or rosuvastatin 20–40) targeting LDL <70.

— Answer: Check ABI first — confirm >0.8 before compression.

— Answer: DAPT 1–6 months, then single antiplatelet ± low-dose rivaroxaban.

— Answer: Atheroembolism — supportive care, statin, avoid further instrumentation.

— Answer: Leriche syndrome — aortoiliac PAD.

— Answer: Refer to vascular surgery for revascularization discussion.

Board pearl: When stem describes "rest pain improved by dangling the foot," answer involves CLTI and urgent vascular surgery referral, not just more medications.

Stem 1 — Classic claudication: 65-year-old smoker with bilateral calf pain at 2 blocks, relieved by 5 min standing rest. Pulses diminished. Best next step?

Stem 2 — Diabetic with elevated ABI: 70-year-old diabetic with non-healing toe ulcer, ABI 1.45. Next step?

Stem 3 — Acute limb ischemia + AF: 75-year-old with AF off anticoagulation, sudden cold pulseless right leg, contralateral pulses normal. Next step?

Stem 4 — Vascular vs neurogenic: 68-year-old with bilateral leg pain when walking, relieved by leaning forward on shopping cart, variable distance, normal pulses.

Stem 5 — Cilostazol contraindication: PAD patient with HFrEF EF 30% asking about med for claudication.

Stem 6 — Buerger disease: 32-year-old male smoker with distal finger and toe ischemia, migratory phlebitis, corkscrew collaterals.

Stem 7 — Statin in PAD: 72-year-old with new PAD, LDL 95.

Stem 8 — Venous ulcer pre-compression: 68-year-old with medial malleolar ulcer about to receive compression.

Stem 9 — Post-endovascular antiplatelet: PAD patient s/p iliac stent.

Stem 10 — Cholesterol embolism: Patient develops blue toes with palpable pulses, livedo, eosinophilia, AKI after cardiac cath.

Stem 11 — Aortoiliac disease: Man with buttock claudication and ED.

Stem 12 — Lifestyle-limiting claudication: After 3 months optimal medical therapy and SET, still limited.

One-Line Recap

— Resting ABI ≤0.90 = PAD; <0.40 = severe/CLTI

— ABI >1.40 → falsely elevated → use TBI (<0.70 abnormal)

— Borderline 0.91–0.99 → exercise ABI (>20% drop or >30 mmHg fall = positive)

— Antiplatelet (clopidogrel 75 or ASA 81; ± rivaroxaban 2.5 BID per COMPASS/VOYAGER)

— High-intensity statin → LDL <70

— ACEi/ARB → BP <130/80

— SGLT2i (not canagliflozin) and/or GLP-1 RA if DM

— Smoking cessation — single highest-impact intervention

— Supervised exercise therapy — first-line for claudication

— Cilostazol for symptoms unless HF

— Foot care, vaccines, one-time AAA US in men 65–75 ever-smokers

Board pearl: PAD = "think CAD of the legs." Same risk factor modification, same secondary prevention bundle, plus limb-specific exercise and selective revascularization.

Step 3 management: When in doubt on test day — ABI first, statin + antiplatelet always, SET before stents, smoking cessation forever.

Bottom line: PAD is a coronary heart disease equivalent diagnosed by ABI (≤0.90, or TBI <0.70 when vessels are calcified) and managed with a lifelong bundle of antiplatelet, high-intensity statin, BP/glucose optimization, smoking cessation, and supervised exercise — with revascularization reserved for lifestyle-limiting symptoms refractory to medical therapy or for chronic/acute limb-threatening ischemia.

Diagnosis cheat-sheet:

Medical bundle (every PAD patient):

Escalation triggers: rest pain, non-healing ulcer, gangrene → urgent vascular referral; 6 Ps of acute limb ischemia → IV heparin + emergent surgery.

Step 3 / CCS reflex: Don't anchor on the limb — PAD patients die of MI and stroke. Treat aggressively as a systemic atherosclerosis disease, integrate transitions of care (DAPT duration, surveillance duplex, PCP communication), and never apply compression without first confirming ABI.