Questioning the predictive role of carotid intima-media thickness

Interest in carotid intima-media thickness (IMT), as a tool to evaluate cardiovascular risk has been driven by studies that demonstrate a relationship between carotid IMT and the incidence of cardiovascular events. However, no study was designed and powered to demonstrate a relationship between changes in carotid IMT during follow-up and cardiovascular events. Therefore, a pooled analysis of existing clinical studies was performed to investigate this relationship. This analysis failed to demonstrate a predictive role of changes in carotid IMT for cardiovascular events. The reason for the lack of clear evidence for a predictive role for changes in IMT are uncertain but may reflect methodological problems related to intra- and inter-observer variability, as it seems unlikely that progression of carotid atherosclerosis would not predict outcome. A further meta-analysis based on individual patient-data has been planned, that may better address this issue. The variability of ultrasound measurements of carotid IMT are likely to be reduced by further development of automatic calculation of this index by MRI.