Edinburgh Napier University

  Introduction
Atrial Fibrillation (AF) affects 30% of the world’s population and accounts for 3 million deaths annually, and current management pathways often result in poor outcomes in recurrence of AF with up to 50% reoccurring post pulmonary vein isolation cardiac ablation (PVICA). Epicardial Adipose Tissue (EAT) is a metabolically active substrate implicated in the pathogenesis of AF. Increased levels of EAT thickness have been associated with the risk of developing AF and has also been associated with poorer outcomes and increased likelihood of AF recurrence after PVICA. 

The aim of this work was to explore current knowledge on levels of EAT in people with AF, post cardiac ablation, taking account of physical activity (PA).

Objectives:  Three research questions were set:

· Does volume of EAT contribute to the pathogenesis and severity of AF?

· Does any kind of PA modify EAT volumes?

· Does PA improve outcomes in patients with AF who have undergone PVICA?

Methods
An umbrella review format was adopted with eligible studies from PubMed, EMBASE, the Cochrane Central Register of controlled trials (CENTRAL), Ovid MEDLINE, CINAHL, and Scopus and registered on Prospero.  All results were reported adhering to Preferred Reporting items for Systematic Reviews and Meta-Analysis (PRISMA).  Quality assessment evaluation involved the AMSTAR 2 tool and risk of bias evaluated using the ROBIS tool.  No ethical considerations were identified for this review.

Results
Ten reviews were eligible for inclusion in the analysis. Five examined the relationship between EAT and AF occurrence, three examined EAT modifications with PA and two examined the effect of PA on AF outcomes.  The quality of the studies was high, with a low risk of bias. Increased EAT volumes were associated with a large effect size for the development of AF Hedges’ g=0.86[0.79,0.92] for Total EAT volume and g=1.31[1.16,1.47] for Left Atrial (LA) EAT volume, and AF severity also had a large effect size for both Total and LA EAT volumes with g=0.87[0.71,1.02] and 0.99[0.69,1.3] respectively. EAT also showed a large effect on recurrence of AF post PVICA in both the Total and LA EAT groups 1.15[0.88,1.43] and 0.92[0.65,1.2].  The overall impact of PA showed a small to medium effect in reducing EAT volumes g=0.23[0,0.46]. Despite this PA was shown to significantly improve outcomes in reducing AF frequency, duration and severity and risk of mortality and serious adverse events in the intervention groups 

Conclusion
Higher levels of EAT are associated with AF after PVICA but the influence of PA is unclear. This review highlights the need for further research evaluating the impact that physical activity has on EAT volume reduction and recurrence of AF post PVICA.