As one of the least expensive and most available markers of atherosclerosis, the ankle-brachial index (ABI) is a highly appropriate measurement for cardiovascular disease risk assessment in the primary-care setting, according to the American Heart Association (AHA) (Circulation. 2012;126:2890-2909).
Originally proposed as a noninvasive means of diagnosing lower-extremity peripheral artery disease (PAD), the ABI now also serves as an indicator of atherosclerosis at other vascular sites. The measure can serve as a prognostic marker for cardiovascular events and functional impairment even in the absence of PAD symptoms.
The AHA statement points out that the ABI — the ratio of the systolic BP measured at the ankle to that measured at the brachial artery — can be determined in about 15 minutes, despite earlier research citing time constraints as a barrier to ABI measurement in primary care.
Another obstacle in the broader use of ABI measurement in general practice is the lack of reimbursement; however, “The standardized ABI measurement proposed in this document has very good test characteristics for the diagnosis of PAD and should be considered for appropriate reimbursement,” wrote the guideline authors.
Patients should be lying flat for an accurate measurement, with head and heels fully supported and not hanging off of the exam table.
The AHA also recommends that the Doppler method be used to measure the systolic BP in each arm and each ankle to obtain the ABI, that cuff size be at least 40% of the limb circumference and that the cuff be placed just above the malleoli with the straight wrapping method.
While noninvasive and safe, ABI measurement by pressure cuff should be interrupted if it is painful for the patient. Cuff inflation should be avoided over a recently placed bypass due to the risk of graft thrombosis, and the ankle cuff should not be placed over open wounds or ulcers.
The AHA also was involved in issuing a clinical guideline focusing on the diagnosis of ischemic heart disease (IHD). With the American College of Physicians, the Society of Thoracic Surgeons, and three other organizations, the AHA coauthored 28 recommendations that address the initial diagnosis of the patient who might have stable IHD, cardiac stress testing to assess the risk for death or MI in patients diagnosed with stable IHD, and use of coronary angiography for risk assessment (Ann Intern Med. 2012;157:729-734).