What does an ABI (Ankle-Brachial Index) reading of 1.04 and 0.72 indicate?

Interpretation of ABI Readings 1.04 and 0.72

The ABI reading of 0.72 indicates peripheral artery disease (PAD) in one leg, requiring further evaluation and management, while the 1.04 reading in the other leg is normal. 1

Understanding ABI Values

ABI readings are interpreted according to the following categories:

• Normal: 1.00-1.40
• Borderline: 0.91-0.99
• Abnormal (PAD): ≤0.90
• Noncompressible vessels: >1.40 2

In this case:

• The 1.04 reading falls within the normal range
• The 0.72 reading indicates definitive PAD

Clinical Significance

For the Leg with ABI 0.72

• This value confirms the diagnosis of lower-extremity PAD as it is well below the diagnostic threshold of 0.90 1
• This level of reduction (ABI <0.8) represents moderate PAD and is associated with:
  • Higher prevalence of severe extracranial carotid disease 3
  • Increased risk of intracranial large artery disease 3
  • Higher incidence of subsequent vascular events at 1 year (19% vs. 11% compared to normal ABI) 3

For the Leg with ABI 1.04

• This value is within normal range and does not suggest PAD in this limb 2
• However, the presence of PAD in one limb indicates systemic atherosclerotic disease

Cardiovascular Risk Assessment

• The abnormal ABI of 0.72 indicates the patient is at increased risk of cardiovascular events and mortality independent of other risk factors 1
• Individuals with an ABI <0.90 have approximately twice the risk of myocardial infarction and cardiovascular death compared to those with normal ABI 1
• The presence of PAD in one limb warrants comprehensive cardiovascular risk assessment 1, 2

Next Steps in Management

1. Complete vascular assessment:

   • Detailed history for symptoms of claudication, rest pain, or tissue loss
   • Physical examination focusing on all peripheral pulses, skin changes, and ulcerations 1
   • Assessment for other vascular beds involvement (coronary, carotid)

2. Cardiovascular risk factor modification:

   • Blood pressure control
   • Lipid management
   • Diabetes management if applicable
   • Smoking cessation if applicable

3. Consider additional testing:

   • Duplex ultrasound to locate and quantify stenotic lesions 1
   • Exercise ABI if symptoms warrant further evaluation 2
   • Consider toe-brachial index if diabetes is present, as ABI sensitivity may be lower in diabetic patients 4

Common Pitfalls in ABI Interpretation

• Unilateral disease: Taking only the higher ABI of both legs may miss significant disease in one limb 1
• Arterial calcification: In diabetic patients or those with chronic kidney disease, vessels may be noncompressible, falsely elevating ABI values 4
• Technical errors: Incorrect cuff placement or patient positioning can affect results 2
• Borderline values: Values between 0.91-0.99 should not be dismissed and may require additional testing 1

The presence of an abnormal ABI in one leg requires prompt vascular consultation to prevent progression of disease and reduce cardiovascular risk.