Heart palpitations and Afib aren't the same thing - you can have palpitations w/o having Afib, but if you have Afib you'll probably have palpitations too - and they don't cause strokes like Afib can. I occasionally have them myself, and have for most of my adult life - feels like my heart stops beating, then beats really hard and fast for a second or two to kind of catch up, first beat feels like my heart is trying to jump out of my chest - can get briefly dizzy when that happens. Have no clue what causes them, usually occur while I'm sitting on the couch watching TV, almost never occur while I'm on my feet or being active. An ex-gf had Afib, and it's an entirely different beast - she would get sick as hell, nauseous, sweating, had to take her to the ER more than once.
Really curious as to what may cause some people to have palpitations from EPA - is it a metabolic issue, or a genetic one, and is the pancreas involved? You need lipase from the pancreas to digest EE-EPA, but don't think you need it for the rTG form - Pharma Restore EPA (name?) is the rTG form, would be interesting for one of you EE-EPA intolerant folks to experiment with that and see if it's the form of EPA that matters or if it's just EPA.