As a CHF patient with a triple bypass under (technically above) my belt, and on 2 gram/ day Metformin for some 15 years or so, I have never had any incidence of AF except immediately after my operation, when I had one attack while they had stopped all my diabetic meds. No recurrence since. In my one incident it was due to the anaesthetic working its way out, and that process upset a lot more of my essential organs on its way out.