Correlations between coronary calcium score, FAI index of epicardial fat inflammation and regional distribution of pericoronary inflammation - insights from the IntelFAT study
Authors: Rosca A , Benedek I , Neicu M , Matyas B B , Blindu E , Rodean I , Halatiu V B , Rat N , Gerculy R , Benedek T 
Published: June 2023

Abstract

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.

Introduction
Coronary calcium score (CCS) is a well-established coronary CT angiography (CCTA) feature associated with the future risk of cardiovascular events. At the same time, coronary inflammation, which can be measured by the recently developed FAI technology at the level of epicardial fat using CCTA, has been proved to be associated with increased plaque-associated risk. However, the correlation between these 2 CT features, both associated with cardiovascular risk, has not been established so far. The aim of the study was to assess the correlation between CCS, as a measure of coronary calcification, and FAI index of coronary inflammation, as a measure of associated inflammation in the coronary tree.

Methods
In total, 169 patients who underwent CCTA were enrolled in the study and divided into two groups according to their calculated CCS: group 1: 54 patients with CCS &lt; 130, and group 2: 115 patients with CCS &gt; 130. In all patients, FAI index of coronary inflammation and associated FAI score centiles were calculated for each coronary artery. The global CT-derived cardiovascular risk was calculated according to both Duke score and CariHeart score, a risk score derived from the FAI index of coronary inflammation and CT phenotype of the coronary plaques.

Results
Patients with high CCS had a higher FAI score (mean FAI score 12.37 +/- 8.33 in group 2 vs 11.65 +/- 7.84 in group 1, p = 0.7). The presence of a high CCS was not significantly associated with the CT-derived Duke score of lesion severity (3.02 +/- 1.38 in group 2 vs 3.09 +/- 1.29 in group 1, p = ns), however the CaRI Heart Risk was significantly higher in the group with high Calcium score (22.88 +/- 19.05 vs 15.95 +/- 11.87, p = 0.0004). At the same time, mapping of inflammation scores along the coronary tree identified that in the group with high CCS, lesions located in the right coronary artery (RCA) had a significantly higher score of inflammation than those in the left coronary artery (Mean FAI score 17.95 +/- 14.56 for RCA versus 11.47 +/- 7.03 for LCA, p = 0.002), while this difference was not significant in patients with lower CCS (p&gt;0.05).

Conclusions
A high level of coronary calcification, as expressed by a high CCS, is associated with an increased level of inflammation at the level of pericoronary fat. At the same time, patients with high CCS present regional differences in distribution of coronary inflammation, showing increased inflammatory reactions especially at the level of the right coronary circulation. This suggests the potential role of geometric and hemorheologic alterations in the complex process of plaque progression.