From the Guidelines
Ankle-Brachial Index (ABI) Ultrasound Usage
ABI ultrasound can be used to assess ankle-brachial index in patients with suspected peripheral artery disease, those at high risk of cardiovascular disease, or those with symptoms of intermittent claudication, such as leg pain during walking 1. It is recommended for patients over 65 years old, smokers, or those with diabetes, and can be performed at rest and after exercise to evaluate blood flow and detect any significant stenosis or occlusion 1.
Key Recommendations
- The resting ABI should be used to establish the lower extremity PAD diagnosis in patients with suspected lower extremity PAD, defined as individuals with 1 or more of the following: exertional leg symptoms, nonhealing wounds, age 65 years and older, or 50 years and older with a history of smoking or diabetes 1.
- The ABI should be measured in both legs in all new patients with PAD of any severity to confirm the diagnosis of lower extremity PAD and establish a baseline 1.
- ABI results should be uniformly reported with noncompressible values defined as greater than 1.40, normal values 1.00 to 1.40, borderline 0.91 to 0.99, and abnormal 0.90 or less 1.
Special Considerations
- In patients with suspected PAD and an ABI >1.40, alternative methods such as the toe-brachial index, Doppler waveform analysis, or pulse volume recording are indicated 1.
- In patients with diabetes, the accuracy of ABI is lower due to medial calcification, and alternative tests such as toe pressure or toe-brachial index may be necessary 1.
Clinical Applications
- ABI ultrasound is a noninvasive, simple, and low-risk test that can be used as a screening tool for PAD in patients at risk 1.
- It can be used to evaluate blood flow and detect significant stenosis or occlusion in patients with symptoms of intermittent claudication 1.
- ABI ultrasound can also be used to monitor disease progression and response to treatment in patients with PAD 1.
From the Research
Ankle-Brachial Index (ABI) Ultrasound Usage
The Ankle-Brachial Index (ABI) ultrasound can be used in the following situations:
- To assess peripheral artery disease (PAD) in patients with symptoms of peripheral ischemia being present at rest or only functionally dependent (intermittent claudication) 2
- To monitor disease progression and assess the benefits of treatment after peripheral vascular intervention (PVI) 3
- As a screening test for the exclusion of PAD in patients at intermediate cardiovascular risk 4
- To identify asymptomatic persons at increased risk of cardiovascular morbidity and mortality, as an ABI <0.9 doubles the risk of death of any cause 2
Diagnostic Accuracy
The diagnostic accuracy of ABI ultrasound is as follows:
- The resting ABI has an overall area under the curve (AUC) of 0.71, while the postexercise ABI yields a similar diagnostic accuracy of AUC 0.72 5
- In the non-diabetes group, the resting ABI has an overall AUC of 0.74 and the postexercise ABI has a similar AUC of 0.76 5
- In the diabetes group, overall accuracy is reduced compared to the non-diabetes group, with the resting ABI having an overall AUC of 0.65 and the postexercise ABI yielding a similar accuracy with an AUC of 0.64 5
Measurement Methods
ABI can be measured using different methods, including: