I've been doing my own personal experiments on myself trying to reduce caffeine intake to help with stress and anxiety. I've felt much better with just a small cutting back of my caffeine intake by taking my "main" cup of coffee (12oz cup) in the morning like I usually do and then just drinking 1/3 caffeinated, 2/3 decaf the rest of the day and going full decaf after 2pm if I have any at all.

I used to drink minimum 36oz (~150mg of caffeine per cup) of coffee per day and it was just turning me into an absolute wreck and just cutting back that little bit has made a huge difference. So instead of 450mg of caffeine, I'm getting ~270mg, so just a little above half the intake and it's made a huge difference.

A-fib just seemed like a natural consequence of the "caffeine peak" and reducing my consumption helped quite a bit.