This study aimed to investigate the relationship between CCTA-based pericoronary inflammation and plaque features as well as local immune-inflammatory biomarkers in ACS patients. It is hypothesized that perivascular FAI might serve as a reliable sensor of coronary immune-inflammatory disorder, and closely related to the plaque vulnerability.

The pericoronary fat attenuation index (FAI), which capture by standard coronary computed tomography angiography (CCTA), has emerged as a novel imaging biomarker of coronary inflammation. This study aimed to assess whether increased Pericoronary FAI on CCTA are associated with high-risk plaque (HRP) feature as well as local T cell subsets and their intracellular cytokines levels in non-ST elevation acute coronary syndromes ( ACS) patients. 195 lesions in 130 non-ST elevation ACS patients were prospectively enrolled and evaluated by CCTA and coronary angiography in this study. Blood were taken from coronary artery immediately after the diagnostic angiogram. Local T cell subsets and their intracellular cytokines levels were detected by Flow Cytometry. CCTA and pericoronary FAI examinations were performed using a 320-detecor (Aquilion ONE, Toshiba Medical Systems, Otawara, Japan) Systems. Coronary plaque characteristics were analyzed cross each of the main coronary arteries using commercialized software package (Qangio CT, Medis, The Netherlands).

Inclusion Criteria:

• non-ST-elevation ACS (non-ST-elevation myocardial infarction or unstable angina) age from 18 to 75 years which underwent CCTA were prospectively enrolled in this study.

Exclusion Criteria:

1. Patients needed an immediate (<2 h) or early invasive strategy (<24 h) according to guidelines were excluded: including those presented with haemodynamic instability or cardiogenic shock, life-threatening arrhythmia or cardiac arrest, mechanical complication, acute heart failure, dynamic ST or T wave changes, GRACE score >140;
2. Subjects with previous history of coronary artery bypass graft surgery or PCI, immune system disorder, tumor, acute/chronic infection, atrial fibrillation, end-stage renal failure, iodine-containing contrast allergy were also excluded.
3. After CCTA performance, we also exclude patients with no significant (≥50%) stenosis on major epicardial vessels and those refused subsequent angiography.
4. Participants with total obstruction on major epicardial vessel, or insufficient image quality for FAI and QangioCT analysis, as well as lack of blood sample were excluded.

Between January 2019 and January 2020, a total of 130 patients with 195 lesions were included in our study for final analysis.