@normanchester I haven't read all the responses. I don't know if this is what you are after, but I'll put it out in case it is helpful.
I have RA and have been taking Omega 3/fish oil for that for 25 years . I take 4 grams daily.
In 2019 after having a bad reaction to a biologic infusion for my RA, I developed extremely high BP and tachycardia. Workup showed Paroximal SVTs. I was put on Metoprolol 25 mg once a day.
In January 2025 I was diagnosed with Mobitz II 2:1 AV heart block and had a dual chamber Pacemaker implanted. My Atrial tachycardia is controlled well with the Metoprolol .
In October 2025, I was in the hospital for pericarditis . None of my workups while in the hospital showed any A-fib. And, So far interrogations of my pacemaker or ECGs have shown A-fib.
I'm aware of the literature suggesting the Connection of Omega 3 and A-fib, so I have worried a little about taking it at that high dose.