Association of Low-Attenuation Noncalcified Plaque Shape and Degree of Intraplaque Embeddedness Using Atherosclerotic Imaging-enabled Quantitative CT with Acute Coronary Syndrome

Purpose To assess the association of low-attenuation noncalcified plaque (LAP) morphologic features, including shape and degree of intraplaque embeddedness, using atherosclerotic imaging-enabled quantitative CT with acute coronary syndrome (ACS). Materials and Methods In this secondary analysis of the Incident Coronary Syndromes Identified by CT (ICONIC) study, a retrospective-nested, case-control, multicenter study of patients with future ACS after coronary CT angiography propensity matched with controls, atherosclerotic imaging-enabled quantitative CT analysis was performed between February and September 2022. LAP morphology was determined qualitatively according to geometric shape (crescent, lobular, spherical, or bean) and degree of intraplaque embeddedness (<90°, 90°-179°, 180°-269°, 270°-360°) within the vessel wall. Shapes were based on visual assessment of LAP contours, including features of curvature, symmetry, and lobulated and protruding components. Adverse LAP morphology (ALM) was defined by morphologic features associated with ACS using log-rank testing. Multivariable Cox regression was performed with ALM as the independent variable, adjusting for plaque burden and diameter stenosis. Results A total of 446 patients (mean age ± SD, 62.44 years ± 11.05; 277 male; 223 cases, 223 controls) with a mean follow-up of 2.45 years ± 2.49 were included in this study. Twenty-two patients were excluded due to missing images or poor image quality. Lobular, bean, and spherical LAP shape or LAP with a degree of intraplaque embeddedness greater than or equal to 180° was associated with increased ACS risk (log-rank P < .05 for each). These morphologic features thus defined ALM. Among 74 of 446 (16.6%) patients with ALM, 57 patients experienced ACS. Patients with ALM had a 3.24-fold increased risk for ACS (adjusted hazard ratio, 3.24 [95% CI: 1.44, 7.30]; P = .005). Conclusion ALM was independently associated with ACS. Keywords: Coronary Angiography, Coronary Arteries ClinicalTrials.gov identifier: NCT02959099 Supplemental material is available for this article.