Interadventitia Common Carotid Artery Diameter Improves Carotid IMT Ability to Predict Coronary Events : Data from the IMPROVE Study : Carotid Intima Media Thickness (IMT) and IMT Progression as Predictors of Vascular Events in a High-Risk European Population

Background: The “IMPROVE study” was designed to investigate whether cross-sectional carotid artery intima media thickness (IMT) and overall IMT progression are predictors of new vascular events in European individuals at high risk of cardiovascular diseases. Aim In this report we investigated whether the measurement of C-IMT could be combined with inter-adventitial common carotid artery diameter (CCAD) to improve the predictability of cardiovascular events in the improve population. Methods: IMPROVE is a prospective, multicenter, longitudinal, observational study. A total of 3711 subjects (median age 64.4 years; 48% men) with at least three vascular risk factors (VRFs) were recruited in 7 centers in Finland, France, Italy, the Netherlands and Sweden. Collected variables included clinical, biochemical, genetic, socio-economic, psychological, nutritional, and educational data, personal and family history of diseases, drug intake and physical activity. 3703 patients were monitored for a median (IQR) follow-up of 36.2 (35.8-37.4) months. 215 of these patients suffered a first cardiovascular event with an incidence of 19.9 per 1000 person-years. Results: In Cox proportional-hazards regression, all the measures of C-IMT were significantly associated with the risk of the combined end point even after adjustment for VRFs (age, gender, HDL-C, LDL-C, systolic blood pressure, diabetes, hypertension and pack-years) (Ptrend <0.005 for all). CCAD was associated with the risk of events independently of vascular risk factors and C-IMTmax (adjusted HR for 1 SD increase: 1.26, 95% confidence interval: 1.08-1.48, p=0.004). The results for cardio and cerebro-vascular events were in line with those observed with the combined end point. By ROC curves analysis, CCAD alone has about the same predictive capacity of the best predictor among C-IMT variables (IMTmean). When combined, IMTmean and CCAD provided a better predictive capacity than conventional VRFs (c-statistic = 0.653 vs. 0.639). The combination of IMTmean, CCAD and VRFs further improved the total predictive capacity (c-statistic 0.669). Conclusions: CCAD and C-IMT are independent predictors of cardiovascular events in European high-risk patients and together they enhance the predictive capacity of VRFs.