What is the management approach for patients with abnormal Ankle-Brachial Index (ABI) with toe pressure and Pulse Volume Recording (PVG) results indicating Peripheral Arterial Disease (PAD)?

Management of Patients with Abnormal ABI, Toe Pressure, and PVR Results Indicating PAD

Patients with abnormal Ankle-Brachial Index (ABI), toe pressure measurements, and Pulse Volume Recording (PVR) results confirming Peripheral Arterial Disease (PAD) should follow a structured management approach based on disease severity, with initial medical therapy for all patients and consideration of revascularization for those with functionally limiting symptoms or critical limb-threatening ischemia (CLTI). 1

Diagnostic Interpretation and Classification

Understanding ABI Results:

• ABI results should be categorized as 1:
  • Abnormal: ≤0.90
  • Borderline: 0.91-0.99
  • Normal: 1.00-1.40
  • Noncompressible: >1.40

Additional Diagnostic Considerations:

• For noncompressible vessels (ABI >1.40), toe-brachial index (TBI) with waveforms is essential 1
• TBI ≤0.70 is diagnostic of PAD 1
• Toe pressure <30 mm Hg indicates severe ischemia with decreased wound healing potential 1
• PVR and Doppler waveforms help delineate anatomic level of disease (aortoiliac, femoropopliteal, infrapopliteal) 1

Special Testing Scenarios:

• Exercise treadmill ABI testing is valuable when:
  • Resting ABI is normal/borderline but symptoms suggest PAD 1
  • Assessing functional limitations in patients with confirmed PAD 1
  • Up to 31% of patients with normal resting ABI may show abnormal post-exercise ABI 2

Management Algorithm Based on Disease Severity

For All PAD Patients:

1. Medical Therapy (Class I recommendations) 1, 3:

   • Antiplatelet therapy: Aspirin (75-325mg daily) or clopidogrel (75mg daily)
   • Statin therapy: High-intensity with target LDL-C <55 mg/dL or ≥50% reduction
   • Blood pressure control: ACE inhibitors or ARBs preferred
   • Smoking cessation
   • Diabetes management
   • Preventive foot care (especially for patients with diabetes)

2. Exercise Therapy 1, 3:

   • Supervised exercise training program (30-45 minutes, at least 3 times weekly for 12+ weeks)
   • Home-based exercise program if supervised program is unavailable

For Patients with Intermittent Claudication:

1. Add Pharmacologic Therapy:

   • Cilostazol 100mg twice daily (contraindicated in heart failure) 3

2. Evaluate Response to Conservative Management:

   • If symptoms persist and are functionally limiting despite GDMT and structured exercise:
     • Proceed to anatomic assessment for possible revascularization

For Patients with CLTI (Critical Limb-Threatening Ischemia):

1. Urgent Evaluation for Revascularization 1:

   • Toe pressure <30 mm Hg
   • TcPO₂ <30 mm Hg
   • SPP <30-50 mm Hg
   • Presence of nonhealing wounds or gangrene

2. Anatomic Assessment for Revascularization Planning 1:

   • Duplex ultrasound (first-line imaging)
   • CTA or MRA
   • Invasive angiography if needed

Anatomic Assessment for Revascularization

When revascularization is being considered, anatomic assessment should follow this sequence 1:

1. Duplex Ultrasound:

   • First-line imaging to confirm location and severity of stenosis

2. CTA or MRA:

   • For more detailed anatomic characterization when revascularization is planned

3. Catheter Angiography:

   • When non-invasive imaging is inconclusive or during endovascular intervention

Special Considerations

For Patients with Noncompressible Vessels:

• Common in diabetes and end-stage renal disease
• TBI is more reliable than ABI 3
• Additional perfusion assessments (TcPO₂, SPP) may be necessary 1

For Patients with Normal ABI but Symptoms:

• Up to 18.7% of patients with normal ABI (0.9-1.3) may have toe pressure <50 mm Hg, indicating PAD 4
• Exercise ABI testing is crucial to unmask PAD in these patients 2
• Pulse wave analysis from PVR can provide additional diagnostic value 5, 6

Follow-up Monitoring:

• Regular ABI measurements to assess disease progression
• For patients with revascularization:
  • Periodic ABI for synthetic grafts
  • Duplex imaging for vein grafts 3

Common Pitfalls to Avoid

1. Relying solely on ABI in patients with diabetes or renal disease - These patients often have noncompressible vessels, leading to falsely elevated ABI values 1, 3

2. Missing PAD in patients with normal resting ABI - Exercise testing is essential when symptoms suggest PAD despite normal resting ABI 2

3. Underestimating cardiovascular risk in patients with abnormal toe pressure but normal ABI - Low toe pressure is significantly associated with cardiovascular mortality even when ABI is normal 4

4. Neglecting PVR waveform analysis - PVR provides valuable information about distal perfusion and can improve assessment of disease severity, especially in critical limb ischemia 6