A potential relationship between gut microbes and atrial fibrillation: Trimethylamine N-oxide, a gut microbe-derived metabolite, facilitates the progression of atrial fibrillation

Background Emerging evidence indicates gut microbes and their products could activate the autonomic nervous system (ANS), which plays important roles in the initiation and maintenance of atrial fibrillation (AF). Trimethylamine N-oxide (TMAO), a metabolite derived from gut microbes, is associated with cardiovascular diseases. The present study aimed to investigate the role of TMAO in the progression of AF. Methods In part 1: TMAO or saline was locally injected into 4 major atrial ganglionated plexi (GP) to clarify its effect on cardiac ANS and AF inducibility in normal canines. In part 2: TMAO or saline was injected into 4 major atrial GP to test its effect on AF progression in a rapid atrial pacing (RAP)-induced AF model. Results In part 1: Local injection of TMAO significantly increased anterior right GP (ARGP) function and neural activity, shortened ERP values. In part 2, compared with the control group, 6-hour RAP significantly shortened the ERP, widened the ∑WOV, enhanced the ARGP function and neural activity, increased the NGF and c-fos expression, and up-regulated the inflammatory cytokines. TMAO aggravated all of these changes by activating the proinflammatory p65 NF-κB signaling pathway. Conclusions TMAO could increase the instability of atrial electrophysiology in normal canines and aggravate the acute electrical remodeling in a RAP-induced AF model by exacerbating autonomic remodeling. The increased inflammatory cytokines in the GP due to the activation of p65 NF-κB signaling may contribute to these effects.