The role of carotid arterial intima-media thickness in predicting clinical coronary events.

BACKGROUND Carotid arterial intima-media thickness is used as a noninvasive surrogate end point to measure progression of atherosclerosis, but its relation to coronary events has not been fully explored. OBJECTIVE To determine whether carotid arterial intima-media thickness predicts coronary events. DESIGN Long-term follow-up (average, 8.8 years) of a previously assembled cohort of persons who completed the 2-year Cholesterol Lowering Atherosclerosis Study, a randomized arterial imaging trial designed to study the effects of lipid lowering on progression of atherosclerosis. SETTING University-based ultrasonography laboratory. PATIENTS 146 men 40 to 59 years of age who had previously had coronary artery bypass graft surgery. MEASUREMENTS Preintrusive atherosclerosis in the common carotid artery was evaluated every 6 months with B-mode ultrasonography, and intrusive atherosclerosis in the coronary arteries was evaluated at baseline and at 2 years with quantitative coronary angiography. After the trial, the incidences of coronary events (nonfatal acute myocardial infarction, coronary death, and coronary artery revascularization) were documented. RESULTS For each 0.03-mm increase per year in carotid arterial intima-media thickness, the relative risk for nonfatal myocardial infarction or coronary death was 2.2 (95% CI, 1.4 to 3.6) and the relative risk for any coronary event was 3.1 (CI, 2.1 to 4.5) (P < 0.001). Absolute intima-media thickness was also related to risk for clinical coronary events (P < 0.02). Absolute thickness and progression in thickness predicted risk for coronary events beyond that predicted by coronary arterial measures of atherosclerosis and lipid measurements (P < 0.001). CONCLUSION Noninvasive B-mode ultrasonographic measurement of progression of intima-media thickness in the distal common carotid artery is a useful surrogate end point for clinical coronary events.