Any insight or links to correlation of hypothyroidism and AF please? (Actually, I was told my thyroid doesn't work at all.) Or change to size of atria/ventricles over the long term? I have taken Levo for 5 years, and two years ago had AF briefly which was corrected by cardioversion. I take bisoprolol and flecainide to maintain heart rate and rhythm, but I am otherwise healthy and fit.