Preserved flow-mediated dilation but delayed time-to-peak diameter in individuals with metabolic syndrome

Abstract

Introduction: Inconsistent evidences of the metabolic syndrome (MetS) impact on vascular reactivity raise questions on flow-mediated dilation (FMD) discriminatory power for disturbances induced by this clustering of risk factors. Previous reports, however, suggest that covariates such as the follow-up of the artery diameter changes, the arterial size and shear stress affect FMD responses and consequently its discriminatory power for distinctive clinical profiles.

Objective: To determine the impact of MetS on traditional, arterial size- and shear-rate-adjusted FMD, the follow-up-derived time-to-peak diameter (TP), as well as their power for discriminating subjects with this clustering of risk factors from a sample of healthy individuals.

Methods: Twenty-one MetS and ten healthy subjects underwent an assessment of endothelial function via FMD.

Results: Traditional and allometrically scaled FMD did not differ between groups (P>0·05) as well as the approach in which the covariate was the peak diameter shear rate. In the existence of MetS, TP was longer (67·7 ± 16·4 s versus healthy 42·1 ± 16·3 s, P = 0·001). ROC curve analysis indicated that TP (AUC = 0·871 [95% CI, 0·718-1·000]) had greater power of discrimination for MetS than FMD approaches. In addition, TP presented a moderate and significant association with sE-selectin (r = 0·458, P = 0·048).

Conclusion: Time-to-peak diameter (TP) rather than FMD distinguished MetS from a healthy profile. Therefore, at least in subjects with MetS, TP may provide insights into the impact of this clustering of risk factors on the vascular phenotype.

Keywords: doppler; endothelial function; hyperaemia; shear stress; vascular reactivity.