Pericoronary Fat Attenuation Index Is Associated With Vulnerable Plaque Components and Local Immune-Inflammatory Activation in Patients With Non-ST Elevation Acute Coronary Syndrome

Background The pericoronary fat attenuation index (FAI) is assessed using standard coronary computed tomography angiography, and it has emerged as a novel imaging biomarker of coronary inflammation. The present study assessed whether increased pericoronary FAI values on coronary computed tomography angiography were associated with vulnerable plaque components and their intracellular cytokine levels in patients with non-ST elevation acute coronary syndrome. Methods and Results A total of 195 lesions in 130 patients with non-ST elevation acute coronary syndrome were prospectively included. Lesion-specific pericoronary FAI, plaque components and other plaque features were evaluated by coronary computed tomography angiography. Local T cell subsets and their intracellular cytokine levels were detected by flow cytometry. Lesions with pericoronary FAI values >-70.1 Hounsfield units exhibited spotty calcification (43.1% versus 25.0%, P=0.015) and low-attenuation plaques (17.6% versus 4.2%, P=0.016) more frequently than lesions with lower pericoronary FAI values. Further quantitative plaque compositional analysis showed that increased necrotic core volume (Pearson's r=0.324, P<0.001) and fibrofatty volume (Pearson's r=0.270, P<0.001) were positively associated with the pericoronary FAI, and fibrous volume (Pearson's r=-0.333, P<0.001) showed a negative association. An increasing proinflammatory intracellular cytokine profile was found in lesions with higher pericoronary FAI values. Conclusions The pericoronary FAI may be a reliable indicator of local immune-inflammatory response activation, which is closely related to plaque vulnerability. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04792047.