Abstract 3561: Associations of Carotid Plaque Composition with Prior Coronary and Peripheral Artery Events

Abstract

Background: Patients with prior coronary (CAD) or peripheral artery (PAD) events have increased plaque burden in the carotid artery, which is subsequently found to indicate future risks in prospective studies. Carotid MRI is capable of measuring both plaque burden and components (calcification [CA], lipid rich necrotic core [LRNC], intraplaque hemorrhage [IPH]). We sought to determine if certain plaque components detected by MRI are associated with prior CAD and PAD events independently of traditional risk factors and plaque burden. Methods: Subjects with asymptomatic carotid stenosis by ultrasound were referred for a standardized multi-contrast carotid MRI. Plaque area and areas of CA, LRNC and IPH were traced on each cross-sectional slice, which were aggregated to determine plaque volume, presence and percent volumes of components for each subject. Prior CAD events were defined as prior acute coronary syndrome and/or coronary revascularization. Prior PAD events were defined as ABI<0.90 and/or prior peripheral artery revascularization. Logistic regression analysis was used to evaluate the independent associations between plaque compositional variables and prior CAD or PAD events after adjustment for clinical variables and plaque volume. Results: A total of 159 subjects were scanned, of which 36 (22.6%) had prior CAD events, 34 (21.4%) had prior PAD events and 30 (18.9%) had both. The rest 59 (37.1%) subjects, free of both CAD and PAD events, were used as a reference group. All compositional variables were significantly associated with plaque volume. Subjects with prior CAD events (n=66) demonstrated a higher prevalence of IPH (31.8% vs. 13.6%, adjusted OR: 5.16, p=0.006) and larger percent volume of IPH (3.5% vs. 0.8%, adjusted OR: 1.21 per 1% change, p=0.017) compared to the reference group after adjustment for clinical variables and plaque volume. No independent associations were found between prior PAD events and carotid plaque components compared to the reference group. Conclusions: Subjects with prior CAD events appeared to have a higher prevalence of IPH and larger percent volume of IPH given a comparable plaque burden with those without prior events. Prospective studies are needed to evaluate if the composition of asymptomatic carotid plaques provides additional information for CAD risk stratification.