Composition of lower extremity in relation to a high ankle–brachial index

OBJECTIVE: Clinical implications of a high ankle-brachial index (ABI) remain controversial. The involvement of atherosclerotic vascular changes as well as a close positive association with body weight has been postulated. We evaluated possible associations between a high ABI and atherosclerotic and anthropometric parameters. METHODS: Study participants were 407 community residents (68 +/- 8 years). Atherosclerosis was evaluated by arterial pulse wave velocity, carotid hypertrophy, and related plasma markers. Composition of the body trunk and lower extremity was evaluated by computed tomography. RESULTS: The frequency of high ABI individuals (> or =1.3) was 6.6%, and that was higher in men (70.4 vs. 37.4%, P < 0.001). Characteristics included a significantly larger waist circumference (high ABI, 86 +/- 5; normal ABI, 82 +/- 9 cm, P = 0.033), lower high-density lipoprotein-cholesterol (60 +/- 16, 68 +/- 20 mg/dl, P = 0.042), and higher glucose (112 +/- 30, 104 +/- 20 mg/dl, P = 0.044), but not carotid hypertrophy (P = 0.315) and pulse wave velocity (P = 0.828). The high ABI individuals also had a significantly higher values for stature (162 +/- 8, 157 +/- 8 cm, P = 0.002), body weight (64 +/- 9, 56 +/- 10 kg, P < 0.001), and visceral fat area (132 +/- 60, 100 +/- 64 cm, P = 0.012). Femoral muscle area (133 +/- 23, 109 +/- 23 cm, P < 0.001) but not fat area (P = 0.301) was also larger in this group. Multiple regression analysis indicated that female sex (beta = -0.138, P = 0.019) and body weight (beta = 0.288, P < 0.001) were independent determinant for ABI. However, after adding femoral muscle cross sectional area to the model, the latter became the only determinant of ABI (beta = 0.341, P < 0.001). CONCLUSION: Lower extremity composition is a strong determinant of ABI. A high ABI value might not be an adverse maker of atherosclerosis in the general population.