Correlating Toe-Brachial Indices and Angiographically Confirmed Peripheral Artery Disease: A Retrospective Review

Abstract

In advanced peripheral arterial disease (PAD), medial arterial calcification is known to inflate the ankle-brachial index. An alternative method of evaluating symptomatic patients is toe-brachial indexes (TBI), where a ratio less than .7 indicates PAD and less than .4 indicates a severe form. The objective of this retrospective analysis was to investigate the association between TBIs less than .7 and angiographically verified PAD. Patients were required to have either a leg angiogram 13 months prior to or 12 months after a 6-minute walk test. Of the 174 included patients, the mean overall TBI was .450. The mean TBI by location was highest at iliac and infra-geniculate with .544 and lowest at supra-geniculate with .372. Infra-geniculate lesions were also the most frequent (n = 46). A TBI less than .4 was found in 47.7% of patients. TBIs greater than .7 were present in 36 patients; however, only 16 had significant angiographic stenosis. In conclusion, the majority of patients with angiographic PAD had a TBI less than .7, especially less than .4. Contrary to suspicion, infra-geniculate lesions were the most common and had the highest TBI.

Keywords: angiography; ankle-brachial index (ABI); peripheral artery disease (PAD); screening; toe-brachial index (TBI).