ABSTRACT
Background : Although epicardial adipose tissue (EAT) has been proved be associated with atrial fibrillation (AF) and post-ablation AF recurrence, the relationship between EAT and AF after cardiac surgery (AFACS) is not evident, yet.
Objective : In the study, we aim to perform a systematic review and meta-analysis to assess the association between EAT and AFACS and whether it is independent of the measurement methods.
Methods : Systematic reach was implemented until May, 30, 2020, which “atrial fibrillation” and “epicardial adipose tissue” were as the main items in electronic databases. Analysis was stratified by EAT measurement methods into three pooled meta-analyses on 1) total EAT volume, 2) left atrium (LA)-EAT volume and 3) EAT thickness between two groups with and without AFACS, estimating standardized mean difference (SMD) with a random effect model.
Results: Eight articles with ten studies (546 patients) were included. Accordingly, the results of meta-analysis showed that EAT was higher in AFACS subjects, regardless of the methods of EAT measurement.[ total EAT volume: SMD = 0.56 ml; 95% confidence interval (CI) = 0.56-1.10ml, I2 = 0.90, P=0.04; EAT thickness: SMD = 0.85mm; 95% CI = 0.04-1.65mm, I2 = 0.90, P=0.04; LA-EAT volume: SMD = 0.57ml, 95% CI = 0.23-0.92ml, I2 = 0.00, P=0.001.] And there was no evidence of publication bias.
Conclusion : EAT may be a potential marker and therapeutic target for AFACS. However, larger scale studies are still required, and evaluation is needed to for further estimation.
Keywords:Atrial fibrillation; epicardial adipose tissue; cardiac surgery; meta-analysis; echocardiography.
1.Background
Atrial fibrillation (AF) is the most common arrhythmia with an increasing rate of morbidity and mortality 1. AF after an cardiac surgery (AFACS) is the most frequent postoperative complication of cardiac surgical procedures, and occurs in up to 30% patients 2. Although cardiac surgery-associated morbidity and mortality reduced, the incidence of AFACS was almost unchanged 3,4. AFACS may have a negative influence on post-operative results in the long term. It can result in a two-fold increase in all-cause 30-day and 6-month mortality after surgery compared to patients with sinus rhythm5.
Recently, more attention has been drawn to the relationship between epicardial adipose tissue (EAT) and AF because of its inflammatory and endocrine properties 6. EAT is an ectopic adipose tissue, which includes fat depots located between the myocardium and the visceral pericardium, such as pericardial fat, perivascular fat and myocardial steatosis. According to the location, it is easy to understand that the physiological functions of epicardial adipose tissue, including the storage of lipids as an energy supply for cardiomyocytes, protection of autonomic ganglia and nerve tissue, as well as regulation in the diameter and flow of coronary vessels7. Therefore, we speculate that EAT may play a central role in the pathogenesis of cardiovascular disease. A number of studies have shown an increasing relationship between EAT and coronary artery disease, atherosclerosis and the progression of coronary plaque burden 8-10, major adverse cardiovascular events 11 and AF12-15.
The relationship between EAT and AFACS was firstly described by Charilaos et al. 16 in 2014, while more than ten studies have been undergone investigation thus far. However, these studies have been conducted in different populations, operations (Coronary Artery Bypass Grafting or valve replacement), with a variety of EAT measurement methods [computed tomography (CT) or echocardiography], and diverse intervals of follow-up7,16-22. This study was the first attempt to prove the association between AFACS and EAT, via conducting a systemic review and meta-analysis in patients with and without AF occurrence after cardiac surgery.