Anatomic correlates of supra-normal ankle brachial indices

Supra-normal ankle brachial index (ABI) (>1.40), poses diagnostic challenges to determine the presence, location, and severity of peripheral artery disease (PAD). The anatomic distribution of PAD in patients with elevated ABI has not been previously described.

A retrospective review of all patients referred to the Massachusetts General Hospital vascular diagnostic laboratory from 5 January 2006 to 12 January 2011 who had both a supra-normal ABI and contrast arteriography (CA) within 3 months of each other is reported. Angiographic patterns were described using the Trans Atlantic Inter Society Consensus II (TASC II) classification.

One-hundred sixteen limbs were analyzed in 92 patients. Mean age was 71.6 years (± 11.2); 81.5% (75/92) were male; 85.9% Caucasian (79/92); 67.4% diabetics (62/92); 78.3% hypertensive (72/92); 67.4% hypercholesterolemic (62/92); and 64.1% were current or former tobacco users (59/92). Chronic hemodialysis was present in 18.5% (17/92) and 15.2% (14/92) received chronic corticosteroids. Intermittent claudication was present in 46.7% (43/92) and critical limb ischemia in 52.2% (48/92). Aortoiliac, femoral and infra-popliteal involvement per angiography occurred in 14.9% (15/101), 56.1% (60/107), and 84.0% (84/100), respectively. Multilevel disease was present in 48.8% (42/86) of patients. PAD was absent in 4.7% (4/86) of patients. Toe brachial index <0.7 was found in 92% (92/100) of patients with angiographically confirmed PAD.

In symptomatic patients referred to a vascular laboratory who were found to have supra-normal ABI, nearly one half exhibited multilevel PAD, and over 80% had infrapopliteal involvement. A supra-normal ABI in such patients mandates evaluation for the presence and extent of PAD.