This guy isn't a doctor, so I fully expect a backlash from this post, but what he says makes sense. Here he makes the connection between GAS and AF. https://www.youtube.com/watch?v=KgfyyLbEM90
Of particular interest in the following video are the recommendations for treating GAS. In a word...Nutrition. In 2 words...fruits/roots. https://www.youtube.com/watch?v=D80PKETXmIk