CAROTID ULTRASOUND EVALUATION OF SUBCLINICAL ATHEROSCLEROSIS IN 2013: PROGRESS AND PITFALLS
Julius M. Gardin, M.D., Hackensack University Medical Center, NJ, USA
Carotid artery ultrasound intima-medial thickness (IMT) measurements are reported to add predictive value to traditional risk factors for predicting myocardial infarction and stroke. Recently, we reported that the Lifetime Risk algorithm was superior to both 10-year and 30-year Framingham Risk Score (FRS) algorithms in assigning subjects with carotid or femoral plaques to the high-risk FRS category for women aged 20-to-60 years and for men aged =50 years (Postley, … Gardin. J Am Coll Cardiol 2012;59:A420). Furthermore, in the elderly Cardiovascular Health Study cohort, addition of carotid IMT measurements modestly improved 10-year risk prediction for stroke and cardiovascular disease (CVD) beyond a basic FRS model—mainly by down-classifying risk in those not experiencing stroke or CVD. However, addition of information regarding presence or absence of plaque added no incremental benefit to carotid IMT measurements in this cohort (Gardin, et al. Circulation 2012;126:A16019). In our experience, addition of femoral artery to carotid artery ultrasound increased detection of plaques by 31% in men and 56% of women aged 50-64 years (Postley, Gardin, et al. J Am Soc Echocardiogr 2009;22:1145-51).
The progression rate of carotid IMT is associated with relative risk for CVD clinical outcomes. In addition, reduction in carotid IMT progression in lipid-lowering trials has been associated with a reduction in CVD events. However, a meta-analysis (Constanzo, et al. J Am Coll Cardiol 2010;56:2006-20) has questioned the reported association of regression or slowed progression of carotid IMT with reduction in CVD events.
Remaining challenges include the need: (1) to further define the independent predictive value of carotid measurements over clinical (e.g., Framingham) risk assessments and newer serologic markers; (2) to determine comparative performance of carotid ultrasound versus other imaging modalities (e.g., magnetic resonance imaging); (3) to further develop imaging measures of plaque bioactivity; and (4) to establish that use of these imaging techniques favorably impacts on CVD outcomes in a cost-effective manner.