Hi, I dont have this problem so cant give any advice, but I do get palpitations and ectopic beats. I have been doing intermittent fasting on and off for a year or so and my palpitations initially got worse on my fasting days. I found if I ate some sugar they resolved!! I have read loads of stuff and apparently its common, for lots of reasons, and the same when I began Keto. Obviously I cant use sugar as a remedy now, so I've started taking fish oil and magnesium supplements. So far so good, I've only had 2 episodes of bad palpitations in 3 weeks. Still a work in progress me thinks!
Do you have access to a good cardiologist who believes in this way of eating? I'm no doctor but I am a nurse and if I were in your shoes I would feel more comfortable doing this under medical supervision, at least initially. I think there has been some research that has shown the keto diet is beneficial to cardiomyopathy patients in the long term, but Ive not read it or know enough about it to comment.
Good luck and I hope you find it works for you.