The relation between total epicardial fat volume assessed by cardiac CT and the presence of atrial fibrillation

Abstract

Background: Obesity is an important risk factor for atrial fibrillation (AF). Local epicardial fat enclosed by the visceral pericardial sac has been hypothesized to exert local pathogenic effects on cardiac structures. We aimed to characterize the relationship between total epicardial fat volume assessed by noncontrast cardiac CT and AF. Methods: This case control study conducted from May 2013 to December 2014 in cardiology and radiology departments of Benha University Hospitals. Fifty patients with a history of AF were taken up plus control group of 50 reference patients without history of AF. All patients underwent cardiac CT imaging to measure total epicardial fat volume (EFV), together with systemic obesity indices as body mass index (BMI), waist circumference and body weight plus echocardiographic parameters as left atrium (LA) volume index, left ventricular ejection fraction. All these were examined in relation to the presence and chronicity of AF. Results: EFV was significantly associated with the presence of AF (p values < 0.05). Significant positive correlation between EFV and AF chronicity was denoted. Patients with persistent AF had significantly larger EFV versus patients with paroxysmal AF (p value = 0.002). EFV was positively correlated with LA volume index (r = +0.45, p < 0.001). Multivariate logistic regression model for AF risk factors revealed that EFV was the strongest independent risk factor for AF with highest odds ratio (2.13, 95% CI: 1.01–3.06) followed by odds ratio (1.81, 1.55 and 0.8) for LA volume index, waist circumference and BMI respectively. Conclusion: Epicardial fat is associated with the presence of AF and predicts chronicity. These associations are independent to systemic measures of adiposity and sensitive echocardiographic parameters as LA volume index. These findings are consistent with the hypothesis of a local pathogenic effect of epicardial fat on the arrhythmogenic substrate supporting AF.

Keywords

• Atrial fibrillation
• Cardiac CT imaging
• Obesity
• Epicardial fat