The basic connection between COVID and heart is well understood I think. Aa I understand it one effect is the spikes plug into ACE receptors which cause construction of capillaries to the point flow stops and the single file of blood in there coagulates. The famous black “COVID toes” is a visible manifestation. The Moderna “Spikevax” programs your tissue to manufacture the spikes only. The quantity varies by person. These spikes act the same and cause vasoconstriction which also varies by personal sensitivity. Anti coagulation drugs I think are very important with aFib. I was on them when I stupidly took the booster and heart went crazy anyway. I asked a doctor why she didn’t prescribe at least an aspirin to folks getting vaccinated and she said anything that might be construed as causing vaccine hesitancy was severely discouraged.
Off label prescription of angiotensin II blocker meds like Micardis is happening, but I wonder if this is the actual mechanism of heart damage. I still am trying to learn whether damaged heart nerves will regenerate or not. Of course I don’t really know if that’s what I have.

Supposedly, they were waiting for more details regarding heart surgeon/nutritionist, Dr. Steven Gundry's preliminary reporting about inflammatory markers, post shots, that appeared to significantly increase. If correct, we also already know that heart /vascular issues can be related to inflammation, so see if you can locate online his info. It was briefly reviewed by an England PhD, but then more details were needed to delve into this further..and crickets. Anyone find any additional effort on Gundry's paper, or has this gone into a black hole?

I had Afib under control for two years with Tikosyn ( dofetilide ). Then I had my first dose in Feb 2021 second on March 3 rd. On 21 st March I was again in Afib. I informed my cardiologist. He said it can be a coincidence but I was sure it had something to do with Pfizer vaccine. Intent trough two cardioversions but they did not help. Then he suggested we will have ablation. So after a number of tests and MRI I was ready fir ablation. I was very scared.
Got it and was out if Afib but two days later had loose motions and then chronic constipation. It triggered Afib. Then went to ICU got glucose and after few hours was comfortable. Still in Afib. Doctor said he will do one more cardioversions. Fixed the date but before this I was in normal sinus rhythm so cancelled cardioversions. Since September 2021 I am in normal sinus rhythm. Did not take booster. But last meeting with cardiologist he said I should take. If I am back in Afib he will treat me. Afib is less dangerous than COVID. So on 22 April I took my first booster. I am 76 years old. Let me see if Afib does not come back. But I am continuing with Tikosyn and Eliquis ( almost three years now fir Tikosyn and more than four years with Eliquis. If I continue out of Afib he may take away Tikosyn.
Hope my experience helps you to decide. Good luck.