LEP and atrial fibrillation: It is worth mentioning that, in humans, AF has been proposed to supply leptin to the foetal stomach from the moment that the foetus begins swallowing, and this incorporated leptin may play a role in the growth and functional development of the foetal gastrointestinal tract, probably acting via the long form of the leptin receptor (ObRb), as a strong expression of the ObRb receptor has been observed in the foetal digestive tract during this developmental period [20].