title: Preserved flow-mediated dilation but delayed time-to-peak diameter in individuals with metabolic syndrome.
abstract: BACKGROUND
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Laboratory of Exercise Sciences, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Rio de Janeiro.
authors.forename: Igor A
authors.initials: IA
authors.lastname: Fernandes
authors.forename: Allan R K
authors.initials: AR
authors.lastname: Sales
authors.forename: Natália G
authors.initials: NG
authors.lastname: Rocha
authors.forename: Bruno M
authors.initials: BM
authors.lastname: Silva
authors.forename: Lauro C
authors.initials: LC
authors.lastname: Vianna
authors.forename: Antonio C L
authors.initials: AC
authors.lastname: da Nóbrega
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm / Q000098:blood supply / Q000000981:diagnostic imaging; D001774:Blood Chemical Analysis; D001783:Blood Flow Velocity / Q000502:physiology*; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000503:physiopathology*; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology; D010808:Physical Examination; D012307:Risk Factors; D013314:Stress, Mechanical; D018608:Ultrasonography, Doppler; D014664:Vasodilation / Q000502:physiology*; D014741:Video Recording
keywords: doppler; endothelial function; hyperaemia; shear stress; vascular reactivity