A comparison of intima media thickness in the common carotid artery, the bulb and plaque area as predictions of incident atherosclerotic events

Abstract

Background and aims There is a debate on how to evaluate carotid artery intima-media thickness (IMT). We here compared IMT of the common carotid artery (CCA) and bulb with plaque area regarding incident atherosclerotic disease. Methods In the PIVUS study (age 70 at baseline, 53% women, n = 856), IMT-CCA, IMT-bulb and plaque area were measured at ages 70, 75 and 80 years and these three measurements were used in updated Cox proportional hazard analysis. Results Over 15 years follow-up, 135 individuals experienced a first-time atherosclerotic disease (myocardial infarction or ischemic stroke). IMT-CCA was not significantly related to this composite endpoint (p = 0.10). IMT-bulb was significantly related to the endpoint (p = 0.003), but this relationship was attenuated following adjustment for CVD risk factors (p = 0.02). On the contrary, plaque area was consistently related to incident atherosclerotic disease also following adjustment for CVD risk factors (p<0.001). When added on top of traditional risk factors, both IMT-bulb and plaque area, but not IMT-CCA, improved the discrimination compared to the traditional risk factors (+5.2%, p = 0.0026 for IMT-bulb, +3.8%, p = 0.013 for plaque area and 0.0% for IMT-CCA). Conclusion In elderly subjects, both IMT-bulb and plaque area improved the discrimination regarding incident atherosclerotic disease when added to traditional risk factors. This was not seen for IMT-CCA. IMT-CCA was therefore inferior compared to the other two carotid artery ultrasonographic measurements in this sample of elderly subjects.