Increasing Carotid Plaque Echolucency is Predictive of Cardiovascular Events in High-Risk Patients

Purpose: Carotid plaque echolucency seen at ultrasonography (US) is a potential indicator of plaque instability and may help identify patients at risk for major adverse cardiovascular events (MACEs). The authors performed this study to determine whether decreasing gray-scale median (GSM) levels at repeat carotid US examinations are associated with future MACEs. Materials and Methods: The study was approved by the institutional ethics committee and all patients provided informed consent. The authors prospectively studied 574 patients with carotid plaques of at least 30% from a group of 1268 consecutive patients who were initially asymptomatic with respect to carotid disease. GSM levels were determined with carotid US at baseline and after a median of 7.5 months (range, 6–9 months), and the mean change of the GSM was calculated. Patients were then followed up clinically for a median of 3.2 years for the occurrence of composite MACE. Results: During the initial period, the median change in carotid GSM was 2.9 (interquartile range [IQR], −6.9 to 11.0). Of 574 study participants, 230 (40%) showed a reduction of GSM levels and 344 (60%) showed an increase. MACEs were observed in 177 (31%) of the 574 patients. Adjusted hazard ratios for the lowest quartile (GSM change less than −6.9), the second quartile (GSM change between −6.9 and 2.9), and the third quartile (GSM change between 3.0 and 11.0) were 1.71 (95% confidence interval [CI]: 1.09, 2.66), 1.36 (95% CI: 0.86, 2.16), and 1.22 (95% CI: 0.77, 1.95), respectively, compared with the highest quartile (GSM change greater than 11.0) ( P = .018). Conclusion: Increasing echolucency of carotid artery plaques within a 6- to 9-month interval is predictive of midterm clinical adverse events of atherosclerosis. © RSNA, 2008