I have seen a cycle. People are anxious. There is much to be anxious about. This (brain/thinking) anxiety, especially if chronic, sets off physical responses, like heart flutters. ( see allostatic load).
Then, we have a heart problem which needs medical attention. Then we have anxiety about our cardio system's problems, which need more medical attention , which leads to more anxiety.
Try exercise, talk therapy, and meditation.
Note: some say it's possible that a pre- existing arrhythmia condition is what makes one more susceptible to anxieties, not that the anxiety causes the heart condition 🤷‍♂️.