Which diagnostic test is the best initial evaluation for peripheral artery disease (PAD) in a patient with symptoms of calf pain on exertion?

The best initial evaluation for peripheral artery disease (PAD) in a patient experiencing symptoms like calf pain during exertion is the ankle-brachial index (ABI). The ABI is a simple, non-invasive test that compares the blood pressure in the patient's ankle with the blood pressure in their arm. This ratio helps to determine the presence and severity of PAD by assessing how well blood is circulating to the legs.

A low ABI indicates that there is reduced blood flow to the lower extremities, which is characteristic of PAD. This test is widely regarded for its ease of use, cost-effectiveness, and ability to provide immediate results, making it the first-line diagnostic tool for evaluating patients suspected of having PAD.

While other options like the toe-brachial index (TBI) and treadmill exercise tests are valuable in specific cases, they are generally considered after the initial assessment with the ABI. The TBI may be useful in certain patients, particularly those with non-compressible arteries or those with diabetes, while a treadmill exercise test is primarily used to assess the functional impairment and to confirm the diagnosis in borderline cases rather than as an initial diagnostic tool.

No evaluation required is not appropriate, as symptoms of calf pain on exertion strongly suggest the potential presence of