Relationship between epicardial adipose tissue and ventricular fibrillation in Brugada syndrome by cardiac computed tomography analysis
Authors: Yonezu K , Shinohara T , Takahashi M , Harada T , Mitarai K , Hirota K , Abe I , Kondo H , Fukui A , Akioka H , Teshima Y , Yufu K , Takahashi N 
Published: October 2024

Abstract

Background
Fibrofatty changes in the myocardium of the right ventricular (RV) to right ventricular outflow tract (RVOT) in patients with Brugada syndrome (BrS) may contribute to ventricular conduction delay and ultimately in the development of ventricular fibrillation (VF). In patients with atrial fibrillation (AF), inflammatory infiltration of epicardial adipose tissue (EAT) into the atrial muscle, along with reduced quantity and quality of EAT, has been demonstrated to be associated with the development of AF. We hypothesized that EAT in the RVOT from the RV in patients with BrS may lead to organic abnormalities in the ventricular muscle, resulting in VF.

Purpose
The purpose of this study was to evaluate the quantity and quality of EAT in patients with BrS using cardiac computed tomography (CT) and to determine the relationship with the occurrence of VF.

Methods
We retrospectively evaluated 61 of 82 patients with BrS regularly followed in our outpatient clinic from January 2000 to December 2023, who underwent cardiac CT scans. Patients were divided into two groups: those with VF events during follow-up (VF event group) and those without events (VF non-event group). Patient background, various parameters, volume of epicardial adipose tissue (EAT), and CT values from cardiac CT scans were compared between the two groups. EAT volume and CT values were measured for the entire heart and four specific regions: right ventricle (RV-EAT), right ventricular outflow tract (RVOT) to pulmonary artery bifurcation (RVOT-EAT), left ventricle (LV-EAT), and the left coronary artery main trunk circumference (LV summit-EAT) were measured for four specific sites.

Results
Median age at first diagnosis of BrS was 43 years, 98% were male patients, 41 patients (71%) had symptomatic BrS, and 18 patients (31%) had a family history. During a median follow-up of 72 months (30-136 months), 22 patients (38%) had VF events, including 2 arrhythmic sudden deaths. The median time from diagnosis to the first VF event was 14.3 months (4.3-24.5 months). The VF event group had more overall EAT volume (98.3 cm3 [range: 77.4 to 120.3 cm3] vs. 70.1 cm3 [range: 53.8 to 98.0 cm3], P=0.02) and significantly more RV-EAT volume (18.4 cm3 [range: 11.5 to 28.0 cm3] vs. 11.0 cm3 [range: 7.9 to 18.3 cm3], P=0.008). The CT value of RV-EAT was significantly lower in the VF event group (-83.1±6.1 vs -78.0±6.2, P=0.003), although the RV-EAT/LV-EAT density ratio was not different between the two groups (1.01±0.05 vs 0.99±0.07, P=0.14). On the other hand, the density ratio of RVOT-EAT/LV-EAT was significantly lower in the VF event group (0.95±0.08 vs. 1.00±0.08, P=0.03).

Conclusions
EAT analysis via CT in patients with BrS revealed that those experiencing VF events during follow-up tended to exhibit greater RV-EAT volume, lower CT values of RV-EAT, and higher CT values of RVOT-EAT density. These findings suggest EAT involvement in VF occurrence in patients with BrS.