Management of Peripheral Artery Disease with Reduced TBI and ABI
For patients with reduced Toe Brachial Index (TBI) and Ankle-Brachial Index (ABI), a comprehensive management plan should include optimal medical therapy, supervised exercise training, and consideration for revascularization based on symptom severity and limb viability assessment.
Diagnostic Interpretation
ABI and TBI Interpretation
- Normal ABI: 1.00-1.40
- Borderline ABI: 0.91-0.99
- Abnormal ABI (PAD): ≤0.90
- Noncompressible arteries: >1.40 1
- Normal TBI: ≥0.70
- Abnormal TBI: <0.70 1
Additional Assessment for Patients with Reduced TBI/ABI
- For patients with noncompressible arteries (ABI >1.40), TBI is essential for diagnosis 1
- In patients with diabetes or renal failure, TBI measurement is recommended even if ABI is normal 1
- For patients with nonhealing wounds or gangrene with normal/borderline ABI, additional perfusion assessment with TBI, transcutaneous oxygen pressure (TcPO₂), or skin perfusion pressure (SPP) is reasonable 1
Management Algorithm
Step 1: Risk Factor Modification (All Patients)
- Smoking cessation (highest priority)
- Lipid management with high-intensity statin therapy
- Blood pressure control (target <130/80 mmHg)
- Diabetes management (target HbA1c <7%)
- Weight management and dietary modification
- Structured exercise program 1
Step 2: Pharmacological Therapy
- Antiplatelet therapy: Clopidogrel 75 mg daily for established PAD to reduce risk of MI and stroke 2
- ACE inhibitors or ARBs for blood pressure control and cardiovascular risk reduction
- High-intensity statin therapy regardless of baseline LDL levels 1
Step 3: Exercise Therapy
- Supervised exercise training (SET) is recommended as first-line therapy for claudication
- Program should include 30-45 minute sessions
- 3-5 times per week
- For at least 12 weeks 1
- Home-based exercise training when SET is not available 1
Step 4: Revascularization Assessment
- For patients with lifestyle-limiting claudication despite optimal medical therapy and exercise
- For patients with critical limb ischemia (CLI) defined as:
- Ankle pressure <50 mmHg
- Toe pressure <30 mmHg
- TcPO₂ <30 mmHg 1
Anatomic Assessment Methods (in order of preference):
- Duplex ultrasound (first-line)
- CTA or MRA
- Invasive angiography (for CLI or lifestyle-limiting claudication with inadequate response to medical therapy) 1
Special Considerations
For Patients with Nonhealing Wounds
- Use the Wound, Ischemia, and foot Infection (WIfI) classification system to estimate amputation risk 1
- Consider revascularization when:
- Toe pressure <30 mmHg
- TcPO₂ <30 mmHg 1
For Patients with Noncompressible Arteries
- TBI is essential for diagnosis (abnormal if ≤0.70)
- Additional perfusion assessment with TcPO₂ or SPP may be necessary 1
For Patients with Diabetes
- More likely to have calcified, noncompressible vessels
- TBI measurement is recommended even with normal ABI 1, 3
- Higher risk for disease progression and amputation
Monitoring and Follow-up
- Regular ABI/TBI measurements to monitor disease progression
- Assessment of functional status and quality of life
- Evaluation of treatment response with exercise ABI testing when appropriate 4
- Ongoing risk factor modification and medication adherence assessment
Common Pitfalls to Avoid
- Relying solely on ABI in patients with calcified vessels (use TBI instead)
- Delaying revascularization in patients with critical limb ischemia
- Underutilizing supervised exercise therapy
- Inadequate antiplatelet therapy
- Failure to recognize that a normal resting ABI does not exclude PAD in symptomatic patients (consider exercise ABI testing) 5
- Inconsistent ABI measurement techniques leading to diagnostic errors 6
By following this evidence-based management approach, patients with reduced TBI and ABI can experience improved functional status, reduced cardiovascular events, and decreased risk of limb loss.