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 interleukin-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.
Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Yung-Kuo
YK
Lin
Yao-Chang
YC
Chen
Shih-Lin
SL
Chang
Yenn-Jiang
YJ
Lin
Jenn-Han
JH
Chen
Yung-Hsin
YH
Yeh
Shih-Ann
SA
Chen
Yi-Jen
YJ
Chen
D000200:Action Potentials / Q000502:physiology*; D000273:Adipose Tissue / Q000503:physiopathology* / Q000637:transplantation; D000818:Animals; D001281:Atrial Fibrillation / Q000209:etiology* / Q000503:physiopathology*; D006333:Heart Failure / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009924:Organ Culture Techniques; D010496:Pericardium / Q000503:physiopathology* / Q000637:transplantation; D011817:Rabbits