Background and Purpose--We hypothesized that for the prediction or exclusion of aortic thrombi or plaques 4 mm, the combination of intima-media thickness (IMT) and distensibility (DC) of the common carotid arteries would be superior to the measurement of IMT alone.

Methods--We prospectively included 208 stroke patients (mean age, 60 years) undergoing transesophageal echocardiography for screening of aortic plaques. IMT and DC were determined by ultrasound, and DC was quantified by measuring blood pressure and the common carotid arteries diameter change on M-mode ultrasound during the cardiac cycle.

Results--Negative predictive values of IMT <0.9 mm and DC 24x10^-3/kPa for the exclusion of aortic atheroma 4 mm were similar (92.0% and 91.7%, respectively). However, negative predictive values increased to 98.2% and to 100.0% for the exclusion of aortic thrombi when both parameters were combined. Positive predictive values of IMT 0.9 mm and DC <24 were lower (46.3%, 41.1%; respectively), but they also increased in combination (54.3%).

Conclusions--Our findings suggest that IMT and DC represent different vessel wall properties and that measuring both parameters provides optimized characterization of carotid atherosclerosis. Combining IMT and DC increases the predictive power of carotid ultrasound, making transesophageal echocardiography dispensable for assessment of the aorta for those with normal carotid arteries and indispensable for those patients with carotid atherosclerosis.