Yeah, apologies. I also prefer ME, because CF makes it sound like it is still, even though it's no longer thought of as, a mental disorder.
I've had some neurological testing, MRI, CT scan, heart echo, amongst other things but nothing has been found. I'm utterly convinced that much of my afib is vagally induced though. I noticed a few extra beats here and there whenever I change positions, move my head forward or back, tilt downwards or move to the side, and so on. But mostly it gets worse when I'm lying in bed. Particularly on either side.
I've had a whole collection of other health issues going on these last 16 months so my heart has taken a back seat, so-to-speak, since my ablation in 2017. But these past 6 months the activity has become more and more frequent. To the point where, last night, it was pounding so hard whenever I got ectopic beats lying on my left side that I was worried it'd wake up my wife. I have also noticed that the intervals between the extra or early beat and the 'pause' are becoming longer, more so when lying down too.
Whatever the cause, I'm sure that the ME has exacerbated the issue no end, because I also have a seemingly mystery breathing issue that no specialist can actually get to the bottom of.