Regional Differences in the Level of Inflammation Between the Right and Left Coronary Arteries – a Coronary Computed Tomography Angiography Study of Epicardial Fat Attenuation Index in Four Scenarios of Cardiovascular Emergencies

Abstract Introduction The pericoronary fat attenuation index (FAI) is an emerging computed tomography-derived marker for measuring vascular inflammation at coronary vessels. It holds prognostic significance for major cardiovascular events and enhances cardiac risk assessment, complementing traditional risk factors and coronary artery calcium scores. However, the impact of local coronary circulation factors on pericoronary inflammation development in right versus left coronary arteries has not been clearly understood. Objective This study aimed to investigate the regional differences in inflammation levels between the right and left coronary arteries in four clinical scenarios: acute coronary event in the follow-up period, post-COVID patients, recent percutaneous intervention, and unstable angina with significant lesions on native coronary arteries. Methods The study included 153 patients (mean age 62 years, 70.5% male) who underwent clinically indicated coronary computed tomography angiography (CCTA). Vulnerable plaque features were analyzed to identify high-risk plaques. FAI and the FAI score, a score integrating risk factors and age, were calculated for each case at the left anterior descending artery (LAD), circumflex artery (LCX), and right coronary artery (RCA). Results A total of 459 coronary arteries were analyzed. Both FAI and FAI scores were higher in the RCA (15.23 ± 11.97) compared to the LAD (10.55 ± 6.78) and (11.48 ± 6.5) LCX (p = 0.02). FAI values showed a significantly higher level at the RCA (−71.25 ± 7.47 HU) compared to the LCX (−76 ± 7.68 HU) and the LAD (−73.04 ± 8.9 HU, p <0.0001). This trend persisted across all subgroups, including post-COVID CT scans (−75.49 ± 7.62 HU for RCA vs. −72.89 ± 9.40 HU for the LCX vs. −71.28 ± 7.82 HU for the LAD, p = 0.01) and patients with high-risk plaques (20.98 ± 16.29 for the RCA vs. 11.77 ± 7.68 for the LCX vs. 12.83 ± 6.47 for the LAD, p = 0.03). Conclusion Plaques in different coronary areas show varied vulnerability and inflammation levels. The RCA, in particular, demonstrates greater inflammation susceptibility, with higher inflammation scores in areas surrounding the coronary plaques.