Is epicardial fat depot associated with atrial fibrillation? A systematic review and meta-analysis

Aims: Atrial fibrillation (AF) is the leading rhythm disorder in western countries. A direct relationship between left atrium (LA) enlargement and electromechanical remodelling has been established. A causative link between epicardial fat (EF), visceral adipose tissue deposited around the heart, and AF has been hypothesized. Several reports suggested the association between EF and the presence of AF. The aim of this study was to verify the relationship between AF and EF depot, performing a meta-analysis of observational case series studies. Methods and results: Studies were identified by searching electronic databases by two independent investigators using 'atrial fibrillation' and 'epicardial fat' as keywords. Comparisons between healthy participants and AF cases were performed using a random effect meta-analysis estimating standardized mean difference among comparison groups. Meta regression was used to address the effect given by potential biological and technical confounders. Through a search result of 502 articles, only 7 were selected to conduct the present study. The comparison between all AF with respect to healthy participants resulted in a 32.0 ml of EF difference (95% confidence interval (CI) = 21.5, 42.5) showing that EF volume is higher in AF cases. A statistical significant difference of EF was observed when comparing both persistent and paroxysmal AF subtypes with respect to healthy participants (EF difference 48.0 ml (95% CI = 25.2, 70.8) and 15.7 ml (95% CI = 10.1, 21.4) for persistent and paroxysmal, respectively). A significant EF difference resulted also when comparing persistent to paroxysmal AF subtypes (29.6 ml (95% CI = 12.7, 46.5)). Conclusions: The present work expands the strength of previously reported association between EF amount and atrial arrhythmia.