Common carotid artery diameter as a marker of cardiovascular risk: preliminary results of the improve study

Background: The “IMPROVE study” was designed to investigate whether cross-sectional carotid artery intima media thickness (IMT) and overall IMT progression are predictors of vascular events in European individuals at high cardiovascular risk. Aim: To investigate whether C-IMT could be combined with inter-adventitial common carotid artery diameter (ICCAD) to improve the predictability of vascular events. Methods: IMPROVE is a prospective, multicenter, longitudinal, observational study. 3711 subjects (median age 64.4 years; 48% men) with at least 3 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 patients suffered a first vascular event with an incidence of 20/1000 person-years. Results: In Cox proportional-hazards regression, C-IMTs were associated with vascular risk (combined end point) even after adjustment for VRFs (Ptrend <0.005 for all). ICCAD was associated with the risk of events independently of VRFs and C-IMTmax (HRadj for 1 SD increase: 1.26, 95% CI: 1.08-1.48, p=0.004). Results for cardio and cerebro-vascular events were in line with those observed with the combined end point. By ROC curves analysis, ICCAD alone has about the same predictive capacity of the best predictor among C-IMT variables (IMTmean). When combined, IMTmean and ICCAD provided a better predictive capacity than conventional VRFs (c-statistic = 0.653 vs. 0.639). Figure 1: Association of IMTmean-max and ICCAD with the incidence vascular events. The combination of IMTmean, ICCAD and VRFs further improved the total predictive capacity (c-statistic 0.669). Conclusions: ICCAD and C-IMT are independent predictors of cardiovascular events in European high-risk patients and together they enhance the predictive capacity of VRFs.