I`ve had the same thing for many years as well. I went on a total preservative free diet and am amazed at the results! Palpitations are almost zero and I can sleep at night :) Pretty much everything has preservatives in it but eating clean is possible. Just takes lots of research and label reading.....anything manmade has preservatives even if it says it doesn`t. And yeah, I get it - everyone looks at you like you`re crazy. Feels awesome now to tell them, I think my happy face convinces them :) I feel like I`ve gone back in time - I prepare all my own food so I can control what goes in to my food, all natural and preservative free. Takes time and planning but it`s worth it.
Rather than a cardiologist, see your doctor and have a series of blood tests to see if you
are lacking anything. It could be a simple metal or something.