Regional differences in the level of inflammation between right and left sided coronary arteries: a cardiac CT study of epicardial fat attenuation index

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): The CARDIOCOV project - Prototype for personalized assessment of cardiovascular risk and post-Covid myocarditis based on artificial intelligence, advanced medical imaging and cloud computing - financed by UEFISCDI PN-III-P2-2.1-PTE-2021-0450 (Contract Number 108PTE/2022). Background Pericoronary fat attenuation index is a novel CT-derived marker used to quantify vascular inflammation at the level of coronary vessels. It has prognostic value for major adverse cardiovascular events and provides improvements in cardiac risk assessment beside classical risk factors and coronary artery calcium score. However, the influence of local factors related to coronary circulation in the right versus left coronary bed, on the development of pericoronary inflammation, has not been elucidated so far. Purpose The aim of the study was to evaluate the regional differences in the level of inflammation between right and left sided coronary arteries. Methods In total, 153 patients (mean age 62 years, male patients 70.5%) who underwent clinically indicated coronary computed tomography angiography (CCTA) were included in the study. All the plaque features classically associated with vulnerability were evaluated for identification of high-risk plaques. Fat attenuation index (FAI) and the corresponding FAI score (which takes into consideration the risk factors and age) were calculated for all cases at the level of the left anterior descending artery (LAD), circumflex artery (Cx) and right coronary artery (RCA). Results A total of 459 coronary arteries were included in the analysis and both FAI and FAI score were higher at the level of RCA compared with LAD and Cx. FAI score was 15.23±11.97 at RCA vs 10.55±6.78 at LAD and 11.48±6.5 for Cx, p = 0.02. Also, a significantly higher value of FAI at the level of RCA was noted in comparison with the other two coronary arteries: −76±7.68 HU for RCA compared to −73.04±8.9 HU for LAD and −71.25±7.47 HU for Cx, p<0.0001. This difference was maintained in all the study sub-group analysis: for patients undergoing CT scan after COVID infection (−75.49±7.62 HU for RCA vs -72.89±9.40 HU for Cx and −71.28 ±7.82 HU for LAD, p = 0.01), or patients with high-risk plaques (20.98±16.29 for RCA vs 11.77±7.68 for Cx and 12.83±6.47 for LAD, p = 0.03). Conclusion Plaques located in different coronary territories exhibit different vulnerability patterns and different levels of inflammation. RCA seems to have a more pronounced susceptibility to inflammation, right coronary plaques exhibiting higher scores of inflammation in the territories surrounding coronary plaques.