The Ankle-Brachial Index Is Related to Left Ventricular Ejection Fraction in Bonnet Macaques

Abstract

Low ankle-brachial index (ABI) is a marker of peripheral arterial disease associated with higher cardiovascular risk. ABI has been found to be influenced by left ventricular ejection fraction (LVEF), but this relation is confounded by atherosclerosis. Objectives: Since nonhuman primates have a low incidence of atherosclerosis, we sought to evaluate the effect of LVEF on ABI in 24 healthy female bonnet macaques (age 83 ± 21 months). Methods: LVEF was determined by echocardiography during anesthesia with ketamine. ABI was determined using automatic blood pressure cuff. Results: Mean LVEF was 73 ± 6%. Mean ABI was 1.03 (range 0.78-1.17) with similar right and left lower limb values (p = 0.78). On univariate analysis, mean ABI was significantly correlated with LVEF (r = 0.58, p = 0.003) but not with age, crown-rump length or weight. Mean LVEF increased in a stepwise manner from lowest to highest ABI tertile (68 ± 6 vs. 73 ± 4 vs. 77 ± 5%, p = 0.008). On ordinal regression and forced multivariate linear analyses, ABI status was independently related to LVEF. Conclusions: ABI is influenced by left ventricular systolic function but not age, height, weight or mass index in bonnet macaques. Left ventricular systolic function should be accounted for when considering ABI measurements.