Figure 9. Schematic illustration of potential mechanism of sympathetic and parasympathetic hyperinnervation in atrial fibrillation (A–F).

Rapid activation leads to stimulation of atrial myocytes to secrete nerve growth factor (NGF), with organized activation in the left atrial appendage causing the most pronounced effect. Retrograde transport within autonomic axons leads to hypertrophy and stimulation of postganglionic cells in the stellate ganglia and the ganglionated plexi, and it induces global hyperinnervation of the left atrium. This, in turn, promotes persistence of atrial fibrillation.