The Role of Carotid Arterial Intima-Media Thickness in Predicting Clinical Coronary Events

Abstract

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.