Heart failure epicardial fat increases atrial arrhythmogenesis

Background: Obesity is an important risk factor for atrial fibrillation (AF) and heart failure (HF). The effects of epicardial fat on atrial electrophysiology were not clear. This study was to evaluate whether HF may modulate the effects of epicardial fat on atrial electrophysiology. Methods: Conventional microelectrodes recording was used to record the action potential in left (LA) and right (RA) atria of healthy (control) rabbits before and after application of epicardial fat from control or HF (ventricular pacing of 360-400 bpm for 4 weeks) rabbits. Adipokine profiles were checked in epicardial fat of control and HF rabbits. Results: The LA 90% of AP duration was prolonged by control epicardial fat (from 77 ± 6 to 87 ± 7 ms, p <0.05, n = 7), and by HF epicardial fat (from 78 ± 3 to 98 ± 4 ms, p <0.001, n = 9). However, control or HF epicardial fat did not change the AP morphology in RA. HF epicardial fat increased the contractility in LA (61 ± 11 vs. 35 ± 6 mg, p = 0.001), but not in RA. Control fat did not change the LA or RA contractility. Moreover, control and HF epicardial fat induced early and delayed afterdepolarizations in LA and RA, but only HF epicardial fat provoked spontaneous activity and burst firing in LA (n = 3/9, 33.3% vs. n = 0/7, 0%, n = 0/9, 0%, p <0.05). Compared to control fat, HF epicardial fat, had lower resistin, C-reactive protein and serum amyloid A, but similar interluekin-6, leptin, monocyte chemotactic protein-1, adiponectin and adipsin. Conclusions: HF epicardial fat increases atrial arrhythmogenesis, which may contribute to the higher atrial arrhythmia in obesity.