Non-invasive methodology: intima media thickness

The intima-media thickness (IMT) of carotid arteries, measured by high-resolution B-mode ultrasound, is one of the methods of choice for determining the presence and the extent of atherosclerosis. Starting from the initial studies showing a significant correlation with pathohistologic measurements this variable has been widely used to investigate its correlation with vascular risk factors (conventional and not conventional) as well as to investigate the association with the extent of atherosclerosis and end-organ damage of high-risk patients. IMT is now widely accepted as a measure of the atherosclerotic burden and as a predictor of subsequent vascular events. By using specific softwares, which allow the automatic edge detection of the blood-intima and media-adventia interfaces, it is now possible to measure this ultrasonic variable with a very high reproducibility (absolute differences between replicate scans not 12-15 µm). Because of its quantitative nature, carotid IMT (C-IMT) is frequently used in clinical trials also to test the efficacy of therapeutic intervention and a variety of drugs, with different mechanism of action, have been shown to influence C-IMT. In some studies the pharmacologically-induced changes in C-IMT have been also associated with a concomitant reduction of cardiovascular events, which further supports the concept that IMT can be considered as a surrogate index of atherosclerosis. The translation of the concept of C-IMT from biomarker to that of surrogate end point, however, requires additional evidence showing that, like cross-sectionally assessed IMT, also C-IMT progression is an effective predictor of new vascular events. Studies, however, aimed at evaluating the relationship between C-IMT progression and cardiovascular events are still required. To this end an observational study, aimed at defining the predictive properties of IMT progression of future cardiovascular events, has been designed. The IMPROVE study is an European, multicentre, longitudinal (three year) ongoing study performed in a population of 3600 patients at high risk of cardiovascular events. The results of this study are expected by 2007.