Abstract 16566: The Carotid Atherosclerosis Score Predicts High-Risk Feature Development and Plaque Progression: A Prospective MRI Study
Background The Carotid Atherosclerosis Score (CAS) has been shown to stratify atherosclerotic disease severity in cross-sectional studies but its ability to predict future plaque development is unknown. In this prospective study, we investigated the correlation between CAS at baseline and the development of high-risk features - intraplaque hemorrhage (IPH) and surface disruption (fibrous cap rupture or ulceration) - and plaque progression.
Methods One hundred subjects with 50-79% carotid stenosis measured by ultrasound were included in this study. They underwent two multi-contrast carotid MRI scans on a 1.5T scanner with a mean interval of 3.0 ± 0.2 years. Within the common imaging coverage of the two scans of each subject, the most diseased artery was reviewed for the presence and absence of high-risk plaque features, wall volume, maximum wall thickness (MWT), and maximum lipid-rich necrotic core area percentage (LRNC). The CAS was computed from the MWT and LRNC measurements: CAS=1 with MWT<2.0mm, CAS=2 with LRNC40%. Plaque progression was defined as the annualized change in wall volume between baseline and follow up.
Results Of the 73 subjects without high-risk features at baseline, 9 (12.3%) developed at least one high-risk feature over the follow up period (4 with IPH and 7 with surface disruption). There was a significant linear trend between baseline CAS and new high-risk features (p<0.001) with rates 0% (0/8), 4% (2/51), 40% (4/10) and 75% (3/4) for CAS=1, 2, 3, 4. All 7 new surface disruptions occurred in subjects with baseline CAS=3 or 4 and the 4 subjects who developed IPH has a baseline CAS=2 or 3. Progression was measured for the 71 of the 73 subjects who did not develop an ulceration over follow up and there was an overall average progression rate of 14.6 ± 2.8 mm3/year (p<0.001). There was a significant linear trend between average progression and baseline CAS (p=0.017) with progression rates 4.6, 13.9, 18.1, and 49.9 mm3/year.
Conclusion In this prospective study, we conclude that the CAS may be used to predict development of high-risk features and the progression of plaque burden, both of which are important in monitoring patients and evaluating treatment options.
- © 2011 by American Heart Association, Inc.