# Characterization of Cardiac Fat in Atrial Fibrillation Patients Prior to Ablation Treatment
###### Abstract  
Epicardial adipose tissue (EAT) and pericardial adipose tissue (PAT) contribute to the development of left atrial fibrillation (AF). The purpose of this study is to determine the factors influencing cardiac fat, evaluate its impact on heart function, and evaluate its role in the recurrence of AF. Cardiac MRI exams of n = 198 patients with paroxysmal AF were retrospectively analyzed to quantify EAT and PAT. Body mass index (BMI) showed significant associations with increased EAT, PAT, and total cardiac fat, particularly with the total end-systolic area (\(p<0.001\)). Males were associated with increased PAT (\(r=-0.331\), \(p<0.001\)) and EAT (\(r=-0.168\), \(p=0.019\)). Increased PAT end-diastolic volume was also associated with an increase in LV mass (\(r=0.249\), \(p<0.01\)). An inverse relationship between EAT end-systolic area and cardiac index (\(r=-0.220\), \(p<0.01\)) was observed. Although BMI did not significantly affect AF recurrence, overweight patients (36%) experienced slightly more AF recurrence than obese patients (33%). Obesity is substantially associated with an increase in EAT and PAT, while sex appears to play a greater role in PAT than EAT and decreased cardiac function.  
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thickness is associated with metabolic syndromes and an increased risk of cardiovascular diseases [13]. In-vivo and ex-vivo studies suggest that the accumulation of EAT can also potentially impact the left ventricle (LV) diastolic function [14; 15; 16]. Moreover, pericardial adipose tissue (PAT), which refers to fat deposits outside the epicardium, causes cardiovascular dysfunction [17]. An increment in PAT has been linked to a rise in the incidence, severity, and recurrence of AF seen in obesity [18]. The impact of the fat around the heart and AF remains unclear. Thus, quantifying EAT and PAT are important parameters that can help identify patients who may be at risk for cardiovascular events.  
Different imaging modalities can measure cardiac fat deposits, such as cardiac computed tomography (CCT), which was proposed as a gold standard for quantifying the EAT volume. However, due to the significant amount of ionizing radiation, CCT poses a potential health risk to the patient [19]. This limitation was surmounted by the introduction of cardiac magnetic resonance imaging (MRI), which can measure cardiac function, morphology, perfusion, and myocardial tissue in a single exam with minimal, if any, impact on patients' health. In the current study, therefore, we aim to assess the factors that influence EAT and PAT fat in AF using cardiac MRI.  
The study's hypotheses are: (1) an increase in BMI and subsequent obesity will be associated with increased cardiac fat deposition; (2) an increase in cardiac fat will have a functional impact on the heart, i.e., LV deterioration; and (3) there will be an increased incidence of AF recurrence in patients with higher cardiac fat deposits. The specific objectives of the study are: (1) to characterize parameters that influence cardiac fat; (2) to assess the effect of cardiac fat on the functional parameters of the heart; and (3) to assess the role of cardiac fat in AF recurrence.