Carotid Plaque Composition Assessed by CT Predicts Subsequent Cardiovascular Events among Subjects with Carotid Stenosis

Abstract

Background and purpose: Currently, the characteristics of carotid plaques are considered important factors for identifying subjects at high risk of stroke. This study aimed to test the hypothesis that carotid plaque composition assessed by CTA is associated with an increased risk of future major adverse cardiovascular events among asymptomatic subjects with moderate-to-severe carotid artery stenosis.

Materials and methods: This single-center, retrospective cohort study included 194 carotid plaques from 176 asymptomatic subjects with moderate-to-severe carotid artery stenosis. The association of CTA-determined plaque composition with the risk of subsequent adverse cardiovascular events was analyzed.

Results: During a median follow-up of 41 months, the adverse cardiovascular event incidence among 194 carotid plaques was 19.6%. There were significant differences in plaque Hounsfield units (P < .001) and spotty calcium presence (P < .001) between carotid plaques from subjects with and without subsequent adverse cardiovascular events. Multivariable analysis revealed carotid plaque Hounsfield unit density (P < .001) and spotty calcium (P < .001) as independent predictors of subsequent adverse cardiovascular events. In association with moderate carotid artery stenosis, the plaque Hounsfield unit values were significantly lower among carotid plaques from subjects who experienced subsequent adverse cardiovascular events (P = .002), strokes (P = .01), and cardiovascular deaths (P = .04); the presence of spotty calcium was significantly associated with the occurrence of adverse cardiovascular events (P = .001), acute coronary syndrome (P = .01), and cardiovascular death (P = .04).

Conclusions: Carotid plaque Hounsfield unit density and spotty calcium were independent predictors of a greater risk of adverse cardiovascular event occurrence.

FIG 1.

Representative figure of plaque Hounsfield unit value measurement. The plaque Hounsfield unit values were measured from noncontrast axial CTA images. An ROI of 2 mm² was preselected on the visually least attenuated area of the plaque at the most stenotic level of contrast-enhanced axial images. Measurements were performed 5 times from the noncontrast axial images using prepositioned ROIs on the plaque. The lowest Hounsfield unit value in each plaque was recorded. ECA indicates external carotid artery.

FIG 2.

Representative figures of high-risk features of carotid plaque (arrowheads) on CTA. Napkin-ring sign (A), carotid plaque ulceration (B), and spotty calcium (C).

FIG 3.

Kaplan-Meier survival analyses of the cumulative event-free rates based on the dichotomization of Hounsfield units at the median value of the cohort (36 HU). Cumulative event-free rates of MACE (A), stroke (B), ACS (C), and CV mortality (D), according to the carotid plaque density. CV indicates cardiovascular.