Regina, this is a question best asked of your physician. I can NOT use a hot tub and even if a bath is too hot and I stay in it too long, my heart rate slows down too much, and I feel like I'm going to pass out. A couple of times I've had to climb out of the tub and lay on the bathroom tile floor to cool off, sometimes for as much as 1/2 an hour till I get to feeling better. And a hot tub is quite a bit hotter than a traditional bathtub.
Again, your best bet is to check with your physician. It may also be dependent on what medications you are on.
As a note, after my heart attack, when I finally awoke, my husband told me he was going to go buy me the hot tub I've ALWAYS wanted. My cardiologist was in the room when he said that, and he stepped right in and said, "Oh, I don't think so..."
I would say why not, my EP said to do what I normally do. I'm interested though in your a-fib diagnosis. I am new to this diagnosis and terrified. Would you share your story with me and the meds you take? Thanks!