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

Objective: To explore whether the measurement of inter-adventitial common carotid artery diameter (CCAD) could be combined with measurement of carotid intimamedia thickness (IMT) to improve predictability of cardiovascular events. Methods: CCAD was measured by ultrasound in 3393 European subjects at high risk of cardiovascular diseases (IMPROVE study). Results: A total of 135 patients suffered a cardiovascular event within 2.47 years (range 0.02-3.13 years). In a Cox analysis, both CCAD and carotid IMT proved to be independent predictors of vascular events (P<0.002 and P<0.0001, respectively). To further investigate the relative roles of CCAD and IMT in predicting future vascular events, we stratified the study population into four groups with CCAD and IMT above or below median. The HR of new events for these four groups, calculated after data adjustment for confounders clearly indicates that the concomitant presence of both variables above the median yields a marked increase in the HR. In fact, compared to patients with both variable below the median, those having just the CCAD above the median showed a hazard ratio of 1.88 (95% CI 0.99, 3.57; p = 0.055), those with just IMT above the median showed a hazard ratio of 1.96 (95% CI 1.04, 3.69; p = 0.037) and those with both variables above the median showed a hazard ratio of 3.01 (95% CI 1.69, 5.38; p = 0.0002), thus clearly indicating an additive predictive capacity. Conclusion: The combination of CCAD with IMT measurement can be used to enhance the predictability of cardiovascular events. Funding: European Project, IMPROVE QLG1-CT-2002-00896