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Carotid atherosclerosis score predicted plaque risk, progression
The carotid atherosclerosis score successfully predicted the development of high-risk plaque features and plaque burden progression in a new study.
The score, which is based on maximum wall thickness and maximum lipid-rich necrotic core percentage, had been tested in a previous cross-sectional study; however, the predictive value was not assessed in a prospective, longitudinal study, according to the study background.
Dongxiang Xu, PhD, of the University of Washington, and colleagues enrolled 120 participants, all of whom were asymptomatic but had 50% to 79% carotid stenosis. The participants underwent MRI scans at baseline and 3 years. Twenty participants were excluded because of poor image quality, insufficient coverage or, in one case, undergoing carotid endarterectomy during the study period.
The primary purpose of the present analysis was to evaluate the association between the carotid atherosclerosis score and incident disrupted luminal surface and intraplaque hemorrhage. For that, researchers analyzed the 73 participants who did not have disrupted luminal surface or intraplaque hemorrhage at baseline.
Of those 73 participants, 12% developed disrupted luminal surface and/or intraplaque hemorrhage during follow-up, the researchers found.
Association established
All participants who developed disrupted luminal surface had a carotid atherosclerosis score of 3 or 4 at baseline, and there was a significant increasing trend for incident disrupted luminal surface with increasing baseline carotid atherosclerosis score (P<.001).
The researchers did not find a similar association between incident intraplaque hemorrhage and increasing baseline carotid atherosclerosis score (P=.3).
To analyze plaque burden progression, the researchers excluded two participants with evidence of new ulceration during follow-up. In the remaining 71 participants, the mean rate of plaque progression was 14.6 mm3 per year. The higher a participant’s baseline carotid atherosclerosis score, the higher his progression rate was likely to be (P=.03), Xu and colleagues wrote.
Predictors compared
The researchers also compared carotid atherosclerosis score with other predictors of new disrupted luminal surface or intraplaque hemorrhage. Carotid atherosclerosis score had the highest area under the curve (0.96; 95% CI, 0.92-1) among predictors for new disrupted luminal surface and among predictors for new disrupted luminal surface or new intraplaque hemorrhage (0.86; 95% CI, 0.71-1). For new intraplaque hemorrhage, predictors with the highest area under the curve included mean normalized wall index and maximized wall thickness (both 0.78); however, neither mean normalized wall index nor maximized wall thickness was significantly associated with new intraplaque hemorrhage.
The carotid atherosclerosis score had the highest correlation with plaque progression rate among predictors (r=0.26; 95% CI, 0.03-0.47) and was the only one with statistical significance.
The researchers cautioned against overinterpretation of these data, given the low number of events. “Nevertheless, the data are promising for a simplification of carotid risk stratification using [carotid atherosclerosis score] and provide strong evidence for conducting future studies that use a larger study sample to validate these initial findings,” Xu and colleagues wrote.
Disclosure: Some researchers report financial ties with Boehringer Ingelheim, Bristol-Myers Squibb, GE Healthcare, Imagepace, Merck, Pfizer, Phillips Healthcare and VPDiagnostics.