The Relationship between Epicardial Fat and Atrial Fibrillation Cannot Be Fully Explained by Left Atrial Fibrosis

Area of Science:

• Cardiology
• Medical Imaging
• Electrophysiology

Background:

• Epicardial adipose tissue (EAT) is implicated in atrial fibrillation (AF) pathogenesis.
• The precise mechanisms linking EAT to AF remain incompletely understood.

Purpose of the Study:

• To quantify the correlation between EAT volume and left atrium (LA) fibrosis.
• To evaluate the predictive value of EAT and LA fibrosis for AF recurrence post-pulmonary vein isolation (PVI).

Main Methods:

• Cardiac CT and CMR imaging were performed in 68 AF patients before PVI.
• EAT volume (EATLM) and LA fibrosis were quantified.
• Patients were followed for AF relapse after PVI.

Main Results:

• A weak but significant correlation was found between EATLM and LA fibrosis (R=0.40, p=0.001).
• AF relapse occurred in 46% of patients during a median follow-up of 22 months.
• EATLM (HR 2.05, p<0.001) and non-paroxysmal AF (HR 2.36, p=0.031) independently predicted AF relapse.

Conclusions:

• LA fibrosis is unlikely the primary mediator linking EAT to AF due to the weak correlation.
• EAT is a stronger predictor of AF relapse post-PVI than LA fibrosis.
• Other, unidentified mediators likely explain the association between EAT and AF.