CAROTID INTIMA-MEDIA THICKNESS IS ONLY WEAKLY CORRELATED WITH THE EXTENT AND SEVERITY OF CORONARY-ARTERY DISEASE

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. Met hods and Results Common carotid IMT was measured by ultrasound in 350 consecutive subjects of age 60+/-10 years (range, 30 to 85 years) on t he day of coronary angiography. Carotid mean IMT was 0.83+/-0.20 mm (r ange, 0.43 to 1.80 mm), and maximum IMT was 1.04+/-0.27 mm (range, 0.4 9 to 2.19 mm). Coronary angiograms were analyzed by independent observ ers for disease severity (number of vessels with greater than or equal to 70% stenosis), extent score, and a modified Gensini score. Mean ca rotid 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, bec ause 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 differ ential effects of these traditional risk factors on the coronary and c ommon carotid arteries. Conclusions Although carotid IMT is significan tly correlated with extent and severity of CAD, the relationship is we ak. This relatively poor correlation (r(2)<.10) should be considered i n the interpretation of clinical trials that use carotid IMT as a surr ogate end point for coronary atherosclerosis.