I have had palpitations all my adult life, but when I was in peri they got worse, particularly at night. I had an ecg at doctors and was referred to see cardiologist and nothing sinister was found...put down to hormones!
My last period was March last year and since then and particularly recently they have been bothersome at night again.
I have never, well so far, had any hot flushes, but I do wonder if it is something similar.
They are awful to have and as you say quite scary.