I am a person who got atrial flutter last October. . Not sure what caused it. I had a cardioversion to stop it, which was successful and now am taking apixiban and metoprolol to help my heart health. When I got my Covid vaccine in March. I had palpitations for about four days following that and then went back into normal rhythm. I had my pneumonia vaccine last week and I had palpitations for a day and then went back into normal rhythm. The cardiologist told me that anytime my immune system gets stressed, either by vaccine or getting sick, Abnormal rhythm is a possibility. He predicted I would go back into normal beats and rhythm, but to let him know if I don’t. I think the metoprolol is helping keeping my heart rate more regular. Good luck, I had my shingles vaccine five years ago so at least that’s under my belt. I know how you feel though, anxious thoughts, about should I or shouldn’t I get the vaccines.