Echolucency of carotid plaque is useful for selecting high-risk patients with chronic coronary artery disease who benefit from intensive lipid-lowering therapy

Abstract

BackgroundUltrasound assessment of the carotid artery provides prognostic information on coronary events. This study examined whether ultrasound assessments of plaque echolucency of the carotid artery are useful for identifying patients with coronary artery disease (CAD) who are at high risk but could benefit from lipid-lowering therapy for secondary prevention. MethodsUltrasound assessment of carotid plaque echolucency with integrated backscatter (IBS) analysis was performed in 393 chronic CAD patients with low-density lipoprotein cholesterol (LDL-C) levels <100 mg/dL on statin therapy. All patients were prospectively followed up for a maximum of 96 months or until the occurrence of one of the following coronary events: cardiac death, nonfatal myocardial infarction, or unstable angina pectoris requiring unplanned revascularization. ResultsDuring the follow-up period, 45 coronary events occurred. Patients were stratified by IBS (≤-16.3 or >-16.3 dB, median value) and LDL-C level (<70 or 70–99 mg/dL). Multivariate Cox proportional hazards analysis showed that patients with lower IBS and LDL-C 70–99 mg/dL had significantly higher probabilities of coronary events compared with those with higher IBS and LDL-C <70 mg/dL, after adjustment for a baseline model of risk factors (hazard ratio 5.15; 95% confidence interval 1.21–22.0, p = 0.03). In contrast, patients with lower IBS and LDL-C <70 mg/dL had an improved prognosis comparable with those with higher IBS. Addition of LDL-C levels to the baseline model of risk factors improved net reclassification improvement (NRI) and integrated discrimination improvement (IDI) in patients with lower IBS (NRI, 0.44, p = 0.04; and IDI, 0.035, p < 0.01), but not in those with higher IBS. ConclusionsEvaluation of echolucency of the carotid artery was useful for selecting CAD patients at high risk of secondary coronary events but who could benefit from lipid-lowering therapy.