title: Racial differences in arterial stiffness and microcirculatory function between Black and White Americans.
abstract: BACKGROUND
  Compared with whites, black Americans suffer from a disproportionate burden of cardiovascular disease (CVD). We hypothesized that racial differences in the prevalence of CVD could be attributed, in part, to impaired vascular function in blacks after adjustment for differences in risk factor burden.
  
  
  RESULTS
  We assessed vascular function in 385 black and 470 white subjects (mean age, 48±11 years; 45% male). Using digital pulse amplitude tonometry (EndoPAT) we estimated the reactive hyperemia index (RHI), a measure of microvascular endothelial function, and peripheral augmentation index (PAT-AIx). Central augmentation index (C-AIx) and pulse-wave velocity (PWV) were measured as indices of wave reflections and arterial stiffness, respectively, using applanation tonometry (Sphygmocor). Compared with whites, blacks had lower RHI (2.1±0.6 versus 2.3±0.6, P<0.001), greater arterial wave reflections assessed as both PAT-AIx (20.4±21.5 versus 17.0±22.4, P=0.01) and CAIx (20.8±12.3 versus 17.5±13.3, P=0.001), and greater arterial stiffness, measured as PWV (7.4±1.6 versus 7.1±1.6 m/s, P=0.001). After adjustment for traditional CVD risk factors, black race remained a significant predictor of lower RHI and higher PAT-AIx and CAIx (all P<0.001) in all subjects and of higher PWV in men (P=0.01). Furthermore, these associations persisted in a subgroup analysis of "healthy" individuals free of CVD risk factors.
  
  
  CONCLUSIONS
  Black race is associated with impaired microvascular vasodilatory function, and greater large arterial wave reflections and stiffness. Because impairment in these vascular indices may be associated with worse long-term outcomes, they may represent underlying mechanisms for the increased CVD risk in blacks.
authors.affiliation: Division of Cardiology, Emory University School of Medicine, Atlanta, GA 30322, USA. aamorr3@emory.edu
authors.forename: Alanna A
authors.initials: AA
authors.lastname: Morris
authors.forename: Riyaz S
authors.initials: RS
authors.lastname: Patel
authors.forename: Jose Nilo G
authors.initials: JN
authors.lastname: Binongo
authors.forename: Joseph
authors.initials: J
authors.lastname: Poole
authors.forename: Ibhar
authors.initials: I
authors.lastname: Al Mheid
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Ahmed
authors.forename: Neli
authors.initials: N
authors.lastname: Stoyanova
authors.forename: Viola
authors.initials: V
authors.lastname: Vaccarino
authors.forename: Rebecca
authors.initials: R
authors.lastname: Din-Dzietham
authors.forename: Gary H
authors.initials: GH
authors.lastname: Gibbons
authors.forename: Arshed
authors.initials: A
authors.lastname: Quyyumi
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D002318:Cardiovascular Diseases / Q000208:ethnology*; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000208:ethnology; D008297:Male; D008365:Manometry; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D063177:Pulse Wave Analysis; D012307:Risk Factors; D059289:Vascular Stiffness / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology; D044465:White People; D055815:Young Adult