Association between coronary inflammation measured by FAT attenuation index and CT features of atheromatous plaque vulnerability

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This research has been funded by the research grant Intel-FAT, proposal registration code PN-III-P4-ID-PCE-2020-2861, contract number PCE 206/2021, Project funded by the European Union and the Government of Romania through the Ministry of European Funds, and the Doctoral School of the “George Emil Palade” University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, Romania. Background Coronary computed tomography angiography (CCTA) is a rapidly evolving tool for the assessment of coronary artery disease (CAD), being able to characterise not only the degree of coronary artery stenosis but also the presence and severity of coronary plaque vulnerability. Fat attenuation index (FAI) is a recently developed marker of coronary inflammation, based on the gradient of CT density at the level of pericoronary fat. Purpose The aim of our study is to investigate the correlation between (1) coronary inflammation as assessed by FAI score, and (2) vulnerability degree of atheromatous coronary plaques, as assesses by presence and severity of CT features of vulnerability at the level of coronary plaques. Methods A total of 54 patients who underwent 128-slice CCTA for chest pain, and having at least one vulnerable coronary plaque, were enrolled in the study. Vulnerable plaques were defined as plaques showing at least one of the following on CT scan: low attenuation plaque, napkin-ring sign, spotty calcifications, or positive remodeling. In total, 114 vulnerable plaques were identified and analyzed using the advanced via Syngo.via Frontier software. FAI score was determined using the FAI technology patented by Caristo. Results The FAI score of coronary inflamamtion was significantly correlated with the total plaque volume at the level of left anterior descendent artery (LAD) (p = 0,01), respectively with the calcified plaque volume at the level of the circumflex artery (p = 0,02). Receiver operating characteristic (ROC) analysis for the correlation between the FAI score and the presence of the Napkin Ring Sign (NRS) showed a significant correlation for plaques located on LAD (AUC 0,729; 95%CI 0,585 – 0,845; p = 0,01), and lefty circumflex artery (AUC 0,745; 95%CI 0,601–0,859; p = 0,032), but not for the right coronary artery (AUC 0,636; 95%CI 0,487–0,767; p = 0,25). Furthermore, the ROC analysis identified a good correlation between the FAI score and the presence of spotty calcification or positive coronary remodeling (AUC 0,777, p = 0,0004, respectively AUC 0,717, p = 0,0081). Conclusion Coronary inflammation measured by FAT attenuation index is significantly correlated with the presence of CT vulnerability features in the coronary tree.