Residual Risk in Non–ST-Segment Elevation Acute Coronary Syndrome: Quantitative Plaque Analysis at Coronary CT Angiography

Background Lipid-rich plaques detected with intravascular imaging are associated with adverse cardiovascular events in patients with non–ST-segment elevation (NSTE) acute coronary syndrome (ACS). But evidence about the prognostic implication of coronary CT angiography (CCTA) in NSTE ACS is limited. Purpose To assess whether quantitative variables at CCTA that reflect lipid content in nonrevascularized plaques in individuals with NSTE ACS might be predictors of subsequent nonrevascularized plaque–related major adverse cardiovascular events (MACEs). Materials and Methods In this multicenter prospective cohort study, from November 2017 to January 2019, individuals diagnosed with NSTE ACS (excluding those at very high risk) were enrolled and underwent CCTA before invasive coronary angiography (ICA) within 1 day. Lipid core was defined as areas with attenuation less than 30 HU in plaques. MACEs were defined as cardiac death, myocardial infarction, hospitalization for unstable angina, and revascularization. Participants were followed up at 6 months, 12 months, and annually thereafter for at least 3 years (ending by July 2022). Multivariable analysis using Cox proportional hazards regression models was performed to determine the association between lipid core burden, lipid core volume, and future nonrevascularized plaque–related MACEs at both the participant and plaque levels. Results A total of 342 participants (mean age, 57.9 years ± 11.1 [SD]; 263 male) were included for analysis with a median follow-up period of 4.0 years (IQR, 3.6–4.4 years). The 4-year nonrevascularized plaque–related MACE rate was 23.9% (95% CI: 19.1, 28.5). Lipid core burden (hazard ratio [HR], 12.6; 95% CI: 4.6, 34.3) was an independent predictor at the participant level, with an optimum threshold of 2.8%. Lipid core burden (HR, 12.1; 95% CI: 6.6, 22.3) and volume (HR, 11.0; 95% CI: 6.5, 18.4) were independent predictors at the plaque level, with an optimum threshold of 7.2% and 10.1 mm3, respectively. Conclusion In NSTE ACS, quantitative analysis of plaque lipid content at CCTA independently predicted participants and plaques at higher risk for future nonrevascularized plaque–related MACEs. Chinese Clinical Trial Registry no. ChiCTR1800018661 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Tavakoli and Duman in this issue.