Presence of Calcium-Like Tissue Composition in Carotid Plaque is Indicative of Significant Coronary Artery Disease in High-Risk Patients

Abstract

Grayscale pixel ranges from ultrasound images, indicating differences in atherosclerotic plaque echogenicity, have been shown to represent different tissue types. Our objective was to determine whether carotid plaque composition was correlated with severity of coronary artery disease (CAD) and risk of cardiovascular (CV) events. A focused carotid ultrasound was performed in 522 participants who had recently undergone coronary angiography. In 468 participants found to have atherosclerotic plaque in at least one carotid artery, plaque composition was assessed for tissue-like types: grayscale ranges 0-4 (blood), 8-26 (fat), 41-76 (muscle), 112-196 (fibrous), and 211-255 (calcium). Logistic regression was used to evaluate correlations with significant CAD (≥50% stenosis). Cox proportional hazards models were used to determine risk for 5-year CV outcomes. Carotid plaque percent fibrous and percent calcium increased with severity of CAD (P<.02). When adjusted for age, sex, body mass index, estimated glomerular filtration rate, and traditional cardiac risk factors, maximum plaque height and percent calcium remained independent contributors of significant CAD (P<.01). Plaque height (≥2.74mm), percent calcium (≥0.11%), and percent fat (11.6%) were associated with increased risk for CV events. Combined plaque height and percent fat gave the highest risk for events (risk ratio=2.02; CI, 1.41-2.94, P=.0002). Carotid plaque fibrous and calcium-like tissues are correlated with increased CAD. Increased percent fat or percent calcium is associated with risk for CV events; however, a combination of plaque height, percent calcium, and/or percent fat increases risk for CV events. Incorporating ultrasound carotid plaque composition into screening practice may improve patient risk stratification for heart disease.