Associations of epicardial, abdominal, and overall adiposity with atrial fibrillation.

Background While adiposity is increasingly recognized as a risk factor for atrial fibrillation (AF), the importance of epicardial fat compared to other adipose tissue depots remains uncertain. We sought to characterize and compare the associations of AF with epicardial fat and measures of abdominal and overall adiposity. Methods and Results We conducted a meta-analysis of 63 observational studies including 352,275 individuals, comparing AF risk for one-standard deviation (1-SD) increases in epicardial fat, waist circumference (WC), waist-to-hip ratio (WHR) and body mass index (BMI). A 1-SD higher epicardial fat volume was associated with a 2.6-fold higher odds of AF (OR 2.61, 95% CI 1.89-3.60), 2.1-fold higher odds of paroxysmal AF (OR 2.14, 95% CI 1.45-3.16) and 5.4-fold higher odds of persistent AF (OR 5.43, 95% CI 3.24-9.12) compared with sinus rhythm. Likewise, a 1-SD higher epicardial fat volume was associated with 2.2-fold higher odds of persistent compared to paroxysmal AF (OR 2.19, 95% CI 1.66-2.88). Similar associations existed for post-ablation, post-operative and post-cardioversion AF. In contrast, associations of abdominal and overall adiposity with AF were less extreme, with relative risks per 1-SD higher values of 1.32 (95% CI 1.25-1.41) for WC, 1.11 (95% CI 1.08-1.14) for WHR, and 1.22 (95% CI 1.17-1.27) for BMI. Conclusions Strong and graded associations were observed between increasing epicardial fat and AF. Moreover, the strength of associations of AF with epicardial fat is greater than for measures of abdominal or overall adiposity. Further studies are needed to assess the mechanisms and clinical relevance of epicardial fat.