Relationship between atrial fibrillation and epicardial adipose tissue

Introduction and purpose: Atrial fibrillation is the most commonly seen type of arrythmia in clinical settings and is associated with increased morbidity and mortality. Although AF pathophysiology is complex, there is increasing evidence supporting the relationship between inflammation and AF .Epicardial fat has been implicated in the pathogenesis of AF by multiple mechanisms because of its proximity to cardiac structures and its sources several proinflammatory cytokines. The main purpose of our study is to determine the correlation of epicardial fat thickness (EFT) measured by echocardiography with the duration of atrial fibrillation. Materials and methods: A total of 80 patients involving twenty control and sixty patients with the diagnosis of AF presenting to our cardiology policlinic between July 2012 and June 2013 were included into the study. To diagnose atrial fibrillation, at the presentation, all the patients had a 12-derivation surface ECG recording by using a 12 gated ECG machine with a 25mm/s velocity and 10mm/mV calibration. According to the classification of patients with chronic atrial fibrillation, they were divided into 3 groups: chronic, paroxysmal, new-onset AF. New-onset AF defines patients with AF diagnosed for the first time; this definition is independent of symptoms or the duration of AF. Paroxysmal AF is often self-terminating AF within 48 hours. In chronic AF, the presence of AF is defined as a patient or physician acceptance. To determine echocardiographic features, we performed a 2-dimensional and M-mode echocardiography (measuring on the free wall of the right ventricle from the parasternal long-axis view) to all of the patients, using a 'General Electrics-Vivid 6' Echocardiography machine. EFT was measured on the free wall of the right ventricle from the parasternal long-axis view.All the data were documented and filed. Results: Each of the other groups of AF consisted of 20 patients. Of the patients, 39 (%49) were female, and 41 (%51) were male. The mean age of the patients was 63 ± 6 years. Hypertension is the most common comorbid situation identified in the patients. EFT was determined to have increased significantly in patients with chronic AF as compared to patients in the control group (5.6 ± 0.9mm vs. 4.2 ±0.9mm, p<0.001). In subgroup analysis of different types of AF, EFT was also observed to have increased remarkably in chronic AF with respect to paroxysmal and new onset AF (4.5 ± 0.9mm and 4.2 ± 1.0mm, respectively). In terms of EFT measurements, there were no significant differences between control and new-onset, paroxysmal AF groups (4.2 ±0.9mm , 4.5 ± 0.9mm and 4.2 ± 1.0mm, respectively). Conclusion: Epicardial adipose tissue thickness was found to be associated with prolonged AF duration. Echocardiographic measurement is an easy and safe method for epicardial fat assessment. Therefore, echocardiographic assesment can be used for risk stratification and diagnosis of CV diseases. Epicardial adipose tissue could be an important target organ for the treatment of AF. Key words: Epicardial fat thickness, echocardiography, atrial fibrillation