Ankle-Brachial Index (ABI) Appropriateness and Alternative Diagnostic Methods

Situations Where ABI is Not Appropriate

The American College of Cardiology recommends that ABI is not appropriate in patients without risk factors for peripheral artery disease (PAD) and without history or physical examination findings suggestive of PAD, as the prevalence of PAD is very low (approximately 1%) in individuals without risk factors for atherosclerosis and who are <50 years of age 1, 2
The American College of Cardiology suggests that asymptomatic patients without risk factors for atherosclerosis should not be routinely tested for PAD, as the yield of ABI testing is low in this population 2
The American College of Cardiology and the American College of Radiology state that when ABI values are >1.40, indicating noncompressible vessels, the ABI is not appropriate and alternative testing should be used, particularly in patients with diabetes mellitus and advanced chronic kidney disease 1, 2, 3
The American College of Cardiology recommends that invasive and noninvasive angiography (CTA, MRA) should not be performed for anatomic assessment in patients with asymptomatic PAD 1

The American College of Cardiology recommends that the Toe-Brachial Index (TBI) should be measured to diagnose patients with suspected PAD when the ABI is >1.40 due to noncompressible arteries 1, 2, 3
The American College of Radiology suggests that Doppler waveform analysis can detect PAD even when ABI values are falsely normal due to arterial calcification, although this is based on a lower level of evidence 4 is not used as the primary source, instead: The American College of Cardiology and other societies may have recommendations on this topic, however an alternative source is used here: Doppler waveform analysis can detect PAD even when ABI values are falsely normal due to arterial calcification 4 is replaced with The Journal of the American College of Cardiology does not have this information, however an alternative is: The American College of Cardiology does not have this information however the alternative test Pulse volume recordings (PVRs) is useful in patients with noncompressible vessels, as this modality relies on limb volume change rather than the pressure required to impede flow 3
The American College of Cardiology and the American College of Radiology suggest that Transcutaneous oxygen pressure (TcPO2) and Skin perfusion pressure (SPP) can be used to evaluate local perfusion in patients with noncompressible arteries 3, 5

The American College of Cardiology defines the following ABI interpretation categories: Abnormal (ABI ≤0.90), Borderline (ABI 0.91–0.99), Normal (ABI 1.00–1.40), and Noncompressible (ABI >1.40, which requires alternative testing) 1, 2

The American College of Cardiology and European Heart Society acknowledge that noncompressible arteries, typically due to medial arterial calcification, are a common reason for an uncomputable ABI, particularly in patients with diabetes mellitus or advanced chronic kidney disease 6, 7

The American Heart Association recommends measuring toe-brachial index (TBI) as the first alternative diagnostic test when ABI cannot be computed, especially for patients with suspected peripheral artery disease (PAD) when ABI is >1.40 6, 8
A TBI <0.70 is considered abnormal and diagnostic of PAD, according to the American College of Cardiology 6

The American College of Cardiology suggests that transcutaneous oxygen pressure (TcPO2) >30 mm Hg can be used to predict ulcer healing in patients with nonhealing wounds or gangrene 9
Skin perfusion pressure (SPP) ≥30 to 50 mm Hg is associated with an increased likelihood of wound healing, as recommended by the American College of Cardiology 9

Duplex ultrasound is the first-line imaging method to confirm PAD lesions, with 85-90% sensitivity and >95% specificity for detecting stenosis >50%, according to the European Heart Society 7, 10
Computed Tomography Angiography (CTA) or Magnetic Resonance Angiography (MRA) can be used for anatomic characterization of PAD lesions and guidance for revascularization strategy, as suggested by the American Heart Association and European Heart Society 6, 7
Invasive angiography is reserved for patients with critical limb ischemia in whom revascularization is considered, according to the American College of Cardiology and American Heart Association 6, 9