Pericoronary fat attenuation index is associated with plaque parameters and stenosis severity in patients with acute coronary syndrome: a cross-sectional study.

Background: The pericoronary fat attenuation index (FAI) is a novel imaging biomarker of coronary inflammation, which is closely related to development and progression of coronary artery disease (CAD). However, there are limited reports on whether elevated pericoronary FAI values from coronary computed tomography angiography (CCTA) were associated with plaque parameters and coronary stenosis in patients with acute coronary syndrome (ACS). We aimed to assessed that FAI helps to identify high risk of CAD. Methods: The clinical diagnosis confirmed to the American Heart Association guidelines for ACS. The lesion-specific pericoronary FAI and plague parameters were measured using QAngioCT software. Using a Hounsfield unit (HU) of -70.1 as the threshold value, lesions with a lesion-specific pericoronary FAI value ≥-70.1 HU were allocated to the FAI-positive group and those with a FAI value <-70.1 HU were allocated to the FAI-negative group. The patients were divided into four stenosis groups according to the coronary angiography (CAG) results, and differences in the FAI values among the four groups were analyzed. Results: A retrospective analysis of 127 ACS patients, including 299 lesions, who underwent CCTA and CAG successively was conducted. The prevalence of vulnerable plaques increased significantly in the FAI-positive group (49.35% vs. 23.87%, P<0.001). The area under the curve (AUC) of FAI in the diagnosis of vulnerable plagues was 0.810. Plaques were closer to the coronary ostium [3.32 (2.83, 4.29) vs. 4.17 (3.33, 4.95) cm, P<0.001] and more often located in the bifurcated segments of the vessels (50.65% vs. 32.43%, P=0.004) in the FAI-positive group than the FAI-negative group. The FAI-positive group also had a higher percentage of diameter stenosis than the FAI-negative group [80.00% (65.00%, 90.00%) vs. 60.00% (40.00%, 85.00%), P<0.001]. FAI values were higher in stenoses with a diameter ≥50% than stenoses with a diameter <50%. Conclusions: The FAI was identified as a novel imaging biomarker of coronary inflammation that is correlated with vulnerable plaque features and stenosis severity.