Epicardial adipose tissue is associated with left atrial volume and fibrosis in patients with atrial fibrillation

Abstract

BackgroundObesity is a risk factor for atrial fibrillation (AF) and strongly influences the response to treatment. Atrial fibrosis shows similar associations. Epicardial adipose tissue (EAT) may be a link between these associations. We sought to assess whether EAT is associated with body mass index (BMI), left atrial (LA) fibrosis and volume.MethodsLA fibrosis and EAT were assessed using late gadolinium enhancement, and Dixon MRI sequences, respectively. We derived 3D models incorporating fibrosis and EAT, then measured the distance of fibrotic and non-fibrotic areas to the nearest EAT to assess spatial colocalization.ResultsOne hundred and three AF patients (64% paroxysmal, 27% female) were analyzed. LA volume index was 54.9 (41.2, 69.7) mL/m2, LA EAT index was 17.4 (12.7, 22.9) mL/m2, and LA fibrosis was 17.1 (12.4, 23.1)%. LA EAT was significantly correlated with BMI (R = 0.557, p < 0.001); as well as with LA volume and LA fibrosis after BSA adjustment (R = 0.579 and R = 0.432, respectively, p < 0.001 for both). Multivariable analysis showed LA EAT to be independently associated with LA volume and fibrosis. 3D registration of fat and fibrosis around the LA showed no clear spatial overlap between EAT and fibrotic LA regions.ConclusionLA EAT is associated with obesity (BMI) as well as LA volume and fibrosis. Regions of LA EAT did not colocalize with fibrotic areas, suggesting a systemic or paracrine mechanism rather than EAT infiltration of fibrotic areas.

MRI-quantified left atrial epicardial adipose tissue predicts atrial fibrillation recurrence following catheter ablation

“…Cardiac MR is currently considered the gold standard in imaging any type of adipose tissue because it has excellent spatial resolution but lacks the ionizing radiation hazards associated with CT. Recently, fat-water separation sequences (e.g., Dixon) proved valuable in detecting pericardial outlines and accurately quantifying EAT (12,20).…”

“…It is also thought to secrete profibrotic factors like tumor growth factor β, matrix metalloproteinases, and activin A, all of which can induce fibrotic remodeling within the myocardial wall with a resultant electrical heterogeneity and local conduction block forming a substrate for AF (10,11). LA EAT was shown to correlate with fibrotic remodeling in the atrial wall (12).…”

Impact of Obesity on Atrial Fibrillation Pathogenesis and Treatment Options

“…Hearts of obese individuals and in preclinical models also show significant accumulation of lipid deposition in the myocardium and pericardium. 19 Evidence of increased cardiac fibrosis has been reported in obese patients and animal models, 18 , 20 although direct causation has not been clearly demonstrated. Below, we discuss mechanisms driving AF in obesity.…”

“… 26 Increased LA EAT volume also independently correlated with greater LA fibrosis and dilatation, which are predictors for AF. 19 Several preclinical studies demonstrate a significant role for EAT in AF pathogenesis (eg, via paracrine signaling) (see subsections Inflammation, Fibrosis, and Oxidative Stress; Neurohormonal Changes; and Electrical Remodeling).…”

Clinical Characteristics and Rhythm Outcomes in Patients With Atrial Myopathy After Successful Catheter Ablation of Atrial Fibrillation

“… 9 , 10 Previous studies have revealed the association between LA EAT and LA volume based on cardiac magnetic resonance imaging in patients with AF. 11 However, there was no clear proof for the associations among atrial myopathy, LV diastolic function, and EAT volume.…”