Elevated pericoronary adipose tissue attenuation assessed by fat attenuation index in atrial fibrillation without cardiovascular comorbidities: a retrospective observational study

Background Atrial fibrillation (AF) without cardiovascular comorbidities is a distinct entity with poorly understood pathophysiology. Inflammation contributes to AF, but pericoronary adipose tissue has not been characterized in this population. We examined the association between pericoronary adipose tissue attenuation, assessed by the fat attenuation index (FAI), an imaging surrogate of inflammation-related adipose tissue remodeling rather than a direct measure of inflammation, and AF without cardiovascular comorbidities. Methods This retrospective, exploratory study included 125 patients undergoing coronary CT angiography (CCTA) for chest pain at two tertiary hospitals: 30 with AF without cardiovascular comorbidities (REGARDS criteria; CAD-RADS 0 coronary arteries) and 95 non-AF controls. Pericoronary FAI and fat volume were measured for the three coronary arteries (LAD, LCX, RCA). Systemic inflammatory ratios (NLR, LMR, PLR) were compared, and logistic regression identified independent predictors. Results FAI was significantly higher in all three coronary arteries, most markedly the RCA (-79.90 ± 7.04 vs. -89.73 ± 10.43 HU, p < 0.001; LAD and LCX both p ≤ 0.008). Although the LMR was lower in the AF group, no FAI measurement correlated with the systemic inflammatory ratios. In multivariable analysis adjusted for age and sex, RCA-FAI (OR 1.11, p < 0.001) and RCA volume (OR 2.38 per SD, p = 0.003) were independent predictors of AF without cardiovascular comorbidities. Conclusions AF without cardiovascular comorbidities is associated with elevated pericoronary FAI that was not explained by routine circulating leukocyte ratios. Given the sample size and the absence of tissue or cytokine confirmation, these findings are hypothesis-generating and require validation in larger prospective cohorts.