title: Echogenicity of medium-to-large carotid plaques predicts future vascular events.
abstract: BACKGROUND
  Although the echolucent plaque in carotid stenosis is associated with future ischemic stroke, the predictive value of echogenicity in small and medium size carotid plaques on vascular events has not been thoroughly examined. Thus, we prospectively tested the hypothesis that plaque echogenicity of carotid atheroma can predict the future total cardiovascular events in patients with vascular risk factors.
  
  
  METHODS
  Ultrasound assessment of carotid intima-media complex thickness (IMT) and plaque echogenicity using integrated backscatter (IBS) analysis was performed in 596 patients aged 40 or more, with any history of vascular events or with at least 1 risk factor, who were enrolled between 2001 and 2006 in the Osaka Follow-up Study for Carotid Atherosclerosis, part 2 (OSACA2). We followed the incidence of total cardiovascular events including cerebrovascular events, coronary heart disease (CHD), and peripheral artery disease (PAD) for 6.4 years. We divided the patients into two groups according to the IBS index above (echorich plaques) and under (echolucent plaque) the median value, and calculated the hazard ratios (HR) of the echolucent group compared with the echogenic group in the risk of cardiovascular events.
  
  
  RESULTS
  Among 596 patients, carotid stenosis was found only in 87 patients. During the follow-up period, we observed 121 cardiovascular events including 63 cerebrovascular events, 45 CHD cases, and 13 PAD cases. The patients with incident cardiovascular events had larger plaque thickness and lower IBS index than those without incident vascular events. The relative risk of vascular events for echolucent versus echorich plaques was 1.45 (95% confidence interval [CI] 0.99-2.13, p = 0.058) after adjustment for risk factors and plaque thickness. In patients with plaque size above the median value (>2.1 mm), the relative risk of vascular events for echolucent plaques was 1.72 (95% CI 1.06-2.85, p = 0.029), but this association was not observed in patients with plaque size <2.0 mm.
  
  
  CONCLUSIONS
  The association between echogenicity of carotid plaque and incident vascular events is dependent on the plaque size. Echolucent medium-to-large plaques, but not small plaques, are associated with the risk of future total cardiovascular events. This finding suggests that measurement of echolucency in medium-to-large carotid plaques may improve selection of patients at high risk for total vascular events.
authors.affiliation: Stroke Division, Department of Neurology, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tadokoro
authors.forename: Manabu
authors.initials: M
authors.lastname: Sakaguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamagami
authors.forename: Shuhei
authors.initials: S
authors.lastname: Okazaki
authors.forename: Shigetaka
authors.initials: S
authors.lastname: Furukado
authors.forename: Mari
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kaori
authors.initials: K
authors.lastname: Miwa
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Yagita
authors.forename: Hideki
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kitagawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002340:Carotid Artery Diseases / Q000175:diagnosis*; D003324:Coronary Artery Disease / Q000175:diagnosis*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D058729:Peripheral Arterial Disease / Q000175:diagnosis*; D011237:Predictive Value of Tests; D012306:Risk; D012307:Risk Factors; D020521:Stroke / Q000150:complications