The utility of ultrasonic tissue characterization of carotid plaque in the prediction of cardiovascular events in diabetic patients

Objective: The aim of this study was to evaluate whether non-invasive ultrasonic tissue characterization of carotid plaque using gray-scale median (GSM) can be a predictor of future cardiovascular disease (CVD) events in type 2 diabetic patients. Methods: A total of 287 type 2 diabetic patients with carotid plaque but without CVD were enrolled (male 72%, mean age 65 +/- 7 years). We prospectively evaluated the association between GSM, a quantitative parameter of the plaque echogenicity, and CVD. Results: The median follow-up period was 55 months, and there were 34 new CVD events. The risk of CVD event was significantly higher in the patients with echolucent (GSM <= 37) plaque (n = 67) as compared to those without (n = 220) (HR = 6.99, 95% CI 3.46-14.14, p < 0.001). Cox proportional hazards regression analysis showed that the presence of echolucent plaque (HR = 4.55, 95% CI 2.10-19.84, p < 0.001) as well as plaque thickness (HR = 1.44, 95% CI 1.01-2.06, p = 0.005) were independent predictors of CVD, even after adjustment for other risk factors. Time-dependent receiver-operating-characteristic curve analysis revealed that the addition of plaque thickness to Framingham risk score (FRS) resulted in significant increase in area under the curve (AUC) [from 0.60 (95% CI; 0.49-0.70) to 0.73 (95% CI; 0.63-0.82), p < 0.05]. Notably, the addition of plaque echogenicity (presence/absence of echolucent plaque) to the FRS and plaque thickness resulted in further and significant increase in AUC [from 0.73 (95% CI; 0.63-0.82) to 0.82 (95% CI; 0.75-0.88), p < 0.05]. Conclusion: Ultrasonic tissue characterization of carotid plaque using the GSM can improve the risk prediction of cardiovascular event in asymptomatic type 2 diabetic patients with carotid plaque. (C) 2013 Elsevier Ireland Ltd. All rights reserved.