Ankle-Brachial Index Test

Test Overview

This test is done by measuring blood pressure at the ankle and in the arm while a person is at rest. Some people also do an exercise test. In this case, the blood pressure measurements are repeated at both sites after a few minutes of walking on a treadmill.

The ankle-brachial index (ABI) result is used to predict the severity of peripheral arterial disease (PAD). A slight drop in your ABI with exercise means that you probably have PAD. This drop may be important, because PAD can be linked to a higher risk of heart attack or stroke.

Why It Is Done

This test is done to check for peripheral arterial disease of the legs.^{footnote 1} It is also used to see how well a treatment is working (such as medical treatment, an exercise program, angioplasty, or surgery).

This test might be done to check your risk of heart attack and stroke. The results can help you and your doctor make decisions about how to lower your risk.

Results

The ABI result can help diagnose peripheral arterial disease (PAD). A lower ABI means you might have PAD. A slight drop in the ABI with exercise, even if you have a normal ABI at rest, means that you probably have PAD.

Normal

A normal resting ankle-brachial index is 1.0 to 1.4. This means that your blood pressure at your ankle is the same or greater than the pressure at your arm, and suggests that you do not have significant narrowing or blockage of blood flow.^{footnote 2}

Abnormal

Abnormal values for the resting ankle-brachial index are 0.9 or lower and 1.40 or higher. If the ABI is 0.91 to 1.00, it is considered borderline abnormal.^{footnote 2}

Abnormal values might mean you have a higher chance of having narrowed arteries in other parts of your body. This can increase your risk of a heart attack or stroke.