Hello, fellow sufferer. Nasty little devil, atrial fibrillation. It is the most common of cardiac problems, and in my case, starts and stops for no apparent reason. I don't always feel great in temperatures over 30 degrees but it upsets my tummy rather than my heart rhythm. The Health Unlocked forum is very useful. Lots of good advice from people who have been diagnosed with AFib. Have a look on You Tube for Sanjay Gupta, a cardiac consultant in York. He has brilliant short clips dealing with all the questions a recently diagnosed person could possibly ask. Good luck and keep well.
My husband has had AF many years . It’s controlled by sotolol still out of rhythm but that slows it . He also takes Apixiban blood thinners . I think the advice in the heat is drink plenty , stay in the shade and don’t over exert yourself - same as anyone really!
My brother had AF takes lots of tablets but he just carries on as normal. I have a heart condition and found the British heart Foundation site very good. Also emailed them with questions and they always answered with plenty of good advice. Worth a try.