Usefulness of the ankle-brachial index in assessing vascular function in normal individuals.

INTRODUCTION

The ankle-brachial index (ABI) has been widely used in the diagnosis of established obstructive peripheral artery disease. However, its applicability in the earlier stages of vascular dysfunction lacks experimental demonstration. Our aim was thus to evaluate the potential of this indicator in the study of vascular function in a normal population.

METHODS

A total of 224 healthy male athletes were enrolled in a cross-sectional study. All underwent measurement of carotid-femoral pulse wave velocity (CFPWV) and carotid-radial pulse wave velocity (CRPWV). Central pulse pressure (PP) was extrapolated from CFPWV and CRPWV using a conversion algorithm (Complior, Colson, Paris). ABI was also calculated (adjusted for body surface area), and casual blood pressure and other relevant anthropometric data were recorded.

RESULTS

The sample's mean age was 20+/-5.64 years, and systolic and diastolic blood pressure were 121+/-10.77 and 67+/-8.67 mmHg respectively. ABI showed a significant inverse correlation with CFPWV (r=-0.455; p<0.001) and with central PP (r=-0.465; p<0.001). Bivariate analysis of the correlation between ABI and left ventricular structural indicators revealed a significant inverse correlation with left ventricular mass (r=-0.43; p<0.05) and left ventricular systolic (r=-0.54; p<0.05) and diastolic (r--0.51; p<0.05) diameters, and with left atrial diameter (r--0.39; p<0.05). Repeated measures ANOVA showed a significant pulse pressure amplification (F (1,071,208,765) = 565.433; p<0.001), with lower values over the aorta (47.9+/-11.01), intermediate values over the brachial artery (54.2+11.66), and higher values over the ankle (74.1+/-15,17). Significant augmentation differences were found between brachial (5.4+/-2.99) and ankle (26.2+/-13.85) territories (F (1, 195) = 427.350; p<0.001). Significant correlations were found between ABI and aorta-ankle PP amplification (r=0.757; p<0.001), as well as with ankle PP (r=0.631; p<0.001).

CONCLUSIONS

The strong association observed between ABI and arterial stiffness indicators, as well as with left ventricular and left atrial structural parameters, strongly supports the idea that this indicator may be useful in clinical practice by improving understanding and identification of potentially important hemodynamic adaptations. Thus, the arterial continuum strongly suggests a broad approach is advisable, integrating information from multiple sources, although the long-term value of the ABI as a potential risk marker remains to be determined in prospective studies.