Diagnostic and Prognostic Performance of Pericoronary Adipose Tissue Attenuation in Suspected Acute Coronary Syndrome: Insights from the RAPID-CTCA Trial

Purpose To assess whether pericoronary adipose tissue (PCAT) attenuation on coronary CT angiography (CCTA) aids in the diagnosis of acute coronary syndrome (ACS) or provides additive prognostic value at 1 year in intermediate-risk individuals. Materials and Methods This study was a secondary post hoc analysis of the multicenter prospective randomized Rapid Assessment of Potential Ischemic Heart Disease with CT Coronary Angiography trial (ClinicalTrials.gov identifier, NCT02284191), which enrolled intermediate-risk patients with suspected ACS from 37 sites in the United Kingdom between March 2015 and June 2019. The current study evaluated the diagnostic and prognostic performance of PCAT attenuation, the Global Registry of Acute Coronary Events (GRACE) score, coronary artery diameter stenosis, and low-attenuation plaque (LAP) burden, using receiver operating characteristic curve analysis and Cox proportional hazards regression, respectively. Results The study included 353 participants (median age, 63 years [IQR, 54-73 years]; 231 [65%] male participants), of whom 169 (48%) had a discharge diagnosis of ACS. The strongest predictors were diameter stenosis (C statistic, 0.74) and LAP burden (C statistic, 0.73), followed by the GRACE score (C statistic, 0.62). PCAT attenuation (C statistic, 0.57) did not provide additive discrimination for diagnosis (<i>P</i> > .05 for all comparisons). Both LAP burden (adjusted hazard ratio, 1.16; 95% CI: 1.02, 1.32) and PCAT attenuation (adjusted hazard ratio, 1.12; 95% CI: 1.00, 1.26) were independent predictors of death or recurrent myocardial infarction at 1 year. However, adding PCAT attenuation (C statistic, 0.63; 95% CI: 0.50, 0.76) to LAP burden (C statistic, 0.69; 95% CI: 0.62, 0.77) did not improve event discrimination (ΔC statistic, 0; 95% CI: -0.11, 0.11; <i>P</i> = .97). Conclusion In intermediate-risk individuals with suspected ACS, PCAT attenuation showed weak diagnostic and prognostic performance, inferior or nonadditive compared with the GRACE score or other CCTA metrics. <b>Keywords:</b> Pericoronary Adipose Tissue Attenuation, Acute Chest Pain, CT Coronary Angiography <i>Supplemental material is available for this article.</i> Clinical trial registration no. NCT02284191 © RSNA, 2026.