Objectives: The purpose of this study was to examine whether echolucent carotid plaques predict future coronary events in patients with clinically stable coronary artery disease (CAD).
Background: Although rupture of coronary plaques is considered a major cause of acute coronary syndromes (ACS), the clinical estimation of coronary vulnerability still remains inconclusive. Ultrasound evaluation of carotid plaques with integrated backscatter (IBS) analysis can indicate the consistency/structure of the plaques. Lipid-rich lesions known as "unstable plaques" appear as echolucent plaques with low IBS values using this technique.
Methods: We investigated the echogenicity of carotid plaques using ultrasound with IBS in 286 consecutive CAD patients (71 with ACS and 215 with stable CAD). Coronary plaque complexity was also determined angiographically in stable CAD patients followed up for 30 months or until the occurrence of coronary events.
Results: The calibrated IBS values of carotid plaques in ACS patients were significantly lower than those in stable CAD patients (p < 0.01). Echolucent carotid plaques accurately predicted the existence of complex coronary plaques (predictive power of 83%). Kaplan-Meier analysis demonstrated a significantly higher probability of coronary events developing in patients with echolucent carotid plaques than in patients without this type of plaque (p < 0.001). The presence of echolucent carotid plaques in stable CAD patients predicted future coronary events independent of other risk factors (odds ratio 7.0, 95% confidence interval 2.3 to 21.4; p < 0.001).
Conclusions: Echolucent carotid plaques with low IBS values predicted coronary plaque complexity and the development of future coronary complications in patients with stable CAD. Qualitative evaluation of carotid plaques using ultrasound with IBS is a clinically useful procedure for risk assessment of CAD patients.