ECHO-LUCENCY OF COMPUTERIZED ULTRASOUND IMAGES OF CAROTID ATHEROSCLEROTIC PLAQUES ARE ASSOCIATED WITH INCREASED LEVELS OF TRIGLYCERIDE-RICHLIPOPROTEINS AS WELL AS INCREASED PLAQUE LIPID-CONTENT

Background-Echo-lucency of carotid atherosclerotic plaques on computer ized ultrasound B-mode images has been associated with a high incidenc e of brain infarcts as evaluated on CT scans. We tested the hypotheses that triglyceride-rich lipoproteins in the fasting and postprandial s tate predict carotid plaque echo-lucency and that echo-lucency predict s a high plaque lipid content. Methods and Results-The study included 137 patients with neurological symptoms and greater than or equal to 5 0% stenosis of the relevant carotid artery, High-resolution B-mode ult rasound images of carotid plaques were computer processed to yield a m easure of echogenicity (gray-scale level). Lipoproteins were measured before and hourly ibr 4 hours after a standardized fatty meal, A subgr oup of 58 patients underwent endarterectomy. On linear regression anal ysis, echu-lucency (low gray-scale level) was associated with elevated levels of fasting and postprandial plasma triglycerides (P=.0002 and P=.002), IDL cholesterol (P=.0009 and P=.006). and VLDL/chylomicron re mnant cholesterol (P=.0003 and P=.0004) and triglycerides (P=.0003 and P=.003), the area under the plasma triglyceride curve 0 to 4 hours af ter a fatty meal (P=.001): and body mass index (P=.0001). On ANCOVA, b ody mass index, fasting IDL cholesterol, and fasting plasma triglyceri des were independent predictors of echo-lucency. Echo-lucency was asso ciated with increased relative plaque lipid content (P=.02). Conclusio ns-Increased plasma levels of triglyceride-rich lipoproteins predict e cho-lucency oi carotid plaques, which is associated with increased pla que Lipid content, Because echo-lucency has been associated with a hig h incidence of brain infarcts on CT scans, triglyceride-rich lipoprote ins may predict a plaque type particularly vulnerable to rupture.