Carotid Intima-Media Thickness and Stiffness are Independent Risk Factors for Atherosclerotic Diseases

Objective We assessed the correlation between intima-media thickness (IMT) and stiffness and test whether they are independent risk factors for atherosclerotic diseases. Methods We enrolled 2333 participants from the general population. Among the study subjects, 197 subjects had a history of stroke or myocardial infarction (MI) and were treated as patients, and the rest were the control subjects. Intima-media thickness was measured at the common carotid artery (CCA), bifurcation, and internal carotid artery. Three parameters (arterial stiffness [β], elastic modulus, and pulse wave velocity) were measured for carotid stiffness. Correlation between IMT and stiffness was first calculated. Multivariate regression model was used to evaluate whether inclusion of both IMT and stiffness can increase the prediction of cardiovascular events. Results Only CCA and bifurcation IMTs were significantly and positively correlated with stiffness. After adjusting for age and sex, the correlations were substantially attenuated. Common carotid artery IMT was most significantly associated with stroke and MI ( P = 2.6 × 10 −8 ) followed by bifurcation IMT ( P = 5.5 × 10 −6 ), and internal carotid artery IMT was least significant ( P = 0.02). For stiffness, β was most significant ( P = 3.6 × 10 −8 ) for stroke and MI, followed by elastic modulus ( P = 1.1 × 10 −6 ) and pulse wave velocity ( P = 6.8 × 10 −6 ). The best model for the combined effect was from β ( P < 0.03) and CCA ( P = 0.056) or bifurcation IMT ( P = 0.057). Conclusions Carotid IMT and stiffness represent different properties of atherosclerotic vessel wall. Measuring both traits provides a better characterization of atherosclerosis.