title: Carotid intima-media thickness is only weakly correlated with the extent and severity of coronary artery disease.
abstract: BACKGROUND
  Intima-media thickness (IMT) of the common carotid artery (CCA), measured with external vascular ultrasound, has been widely used in clinical trials as a surrogate marker for coronary atherosclerosis. Despite this, the degree of correlation between carotid IMT and the extent and severity of coronary artery disease (CAD) is not known.
  
  
  RESULTS
  Common carotid IMT was measured by ultrasound in 350 consecutive subjects of age 60 +/- 10 years (range, 30 to 85 years) on the day of coronary angiography. Carotid mean IMT was 0.83 +/- 0.20 mm (range, 0.43 to 1.80 mm), and maximum IMT was 1.04 +/- 0.27 mm (range, 0.49 to 2.19 mm). Coronary angiograms were analyzed by independent observers for disease severity (number of vessels with > or = 70% stenosis), extent score, and a modified Gensini score. Mean carotid IMT was weakly but significantly correlated with CAD severity (r = .26), extent (r = .23), and modified Gensini score (r = .29, P < .0001 for all correlations). Carotid IMT was not clinically useful, however, because it was not specific or sensitive enough to identify patients with or without significant CAD. Increasing age, male sex, and presence of diabetes were all associated with a significantly (P < .01) higher CAD score than the average for any level of carotid IMT, suggesting differential effects of these traditional risk factors on the coronary and common carotid arteries.
  
  
  CONCLUSIONS
  Although carotid IMT is significantly correlated with extent and severity of CAD, the relationship is weak. This relatively poor correlation (r2 < .10) should be considered in the interpretation of clinical trials that use carotid IMT as a surrogate end point for coronary atherosclerosis.
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, Australia.
authors.forename: M R
authors.initials: MR
authors.lastname: Adams
authors.forename: A
authors.initials: A
authors.lastname: Nakagomi
authors.forename: A
authors.initials: A
authors.lastname: Keech
authors.forename: J
authors.initials: J
authors.lastname: Robinson
authors.forename: R
authors.initials: R
authors.lastname: McCredie
authors.forename: B P
authors.initials: BP
authors.lastname: Bailey
authors.forename: S B
authors.initials: SB
authors.lastname: Freedman
authors.forename: D S
authors.initials: DS
authors.lastname: Celermajer
mesh_terms: D006328:Cardiac Catheterization; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000473:pathology; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography