title: Common carotid artery end-diastolic velocity is independently associated with future cardiovascular events.
abstract: BACKGROUND
  Carotid ultrasound is widely used to measure haemodynamic parameters, such as intima-media thickness and blood flow velocities (i.e. peak-systolic velocity [PSV], end-diastolic velocity [EDV], and resistive index [RI]). However, the association between blood flow velocities and cardiovascular events remains unclear.
  
  
  METHODS
  Baseline data, including quantitative ultrasonography, were obtained from 3146 adults as part of the Cardiovascular Diseases Risk Factor Two-Township Study. Occurrence of ischaemic heart disease (IHD) and stroke was determined from insurance claims and death certificates. The hazard ratio (HR) of CVD (IHD and stroke combined) was calculated for EDV and PSV of the common carotid artery using Cox models. Net reclassification index and integrated discrimination index were used to evaluate the capacity of EDV to predict IHD, stroke, and CVD.
  
  
  RESULTS
  Median follow-up was 12.8 years. There were 220 cases of IHD and 247 cases of stroke. The HR (95% CI) for CVD from univariate analysis was 4.54 (3.51-5.85) for EDV <15 cm/s relative to EDV ≥ 20 cm/s (p < 0.0001), and 3.23 (2.51-4.15) for PSV < 65 cm/s relative to PSV ≥ 80 cm/s (p < 0.0001). The HR (95% CI) for CVD from multivariate analysis was 1.66 (1.22-2.26) for EDV < 15 cm/s relative to EDV ≥ 20 cm/s, and 1.39 (1.03-1.89) for PSV < 65 cm/s relative to PSV ≥ 80 cm/s. EDV slightly but significantly improved prediction of CVD (integrated discrimination index 0.56%, p = 0.016).
  
  
  CONCLUSIONS
  Low common carotid EDV and PSV were independently associated with future CVD, and EDV improved the prediction of future CVD. More prospective studies are required in different ethnic groups to understand the significance and implication of these findings.
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan.
authors.forename: Shao-Yuan
authors.initials: SY
authors.lastname: Chuang
authors.affiliation: Central Laboratory, Shin Kong Wu Ho-Su Memorial Hospital, Taiwan School of Public Health, Taipei Medical University, Taiwan.
authors.forename: Chyi-Huey
authors.initials: CH
authors.lastname: Bai
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taiwan Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taiwan.
authors.forename: Hao-Ming
authors.initials: HM
authors.lastname: Cheng
authors.affiliation: Changhua Christian Hospital Yuan Branch, Yunlin County, Taiwan.
authors.forename: Jiunn-Rong
authors.initials: JR
authors.lastname: Chen
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taiwan.
authors.forename: Wen-Ting
authors.initials: WT
authors.lastname: Yeh
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taiwan Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taiwan.
authors.forename: Pai-Feng
authors.initials: PF
authors.lastname: Hsu
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan.
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Liu
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan Institute of Biomedical Sciences, Academia Sinica, Taiwan pan@ibms.sinica.edu.tw.
authors.forename: Wen-Harn
authors.initials: WH
authors.lastname: Pan
mesh_terms: D001783:Blood Flow Velocity; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging*; D059168:Carotid Intima-Media Thickness; D003971:Diastole; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology*; D013599:Systole; D013624:Taiwan / Q000453:epidemiology; D018615:Ultrasonography, Doppler, Color; D018616:Ultrasonography, Doppler, Duplex
keywords: End-diastolic velocity; ischaemic heart disease; risk assessment and risk reclassification; stroke