As Jenny says, if you google terms like 'steroids' and 'arrhythmia,' you will get a bunch of answers. Much depends on what kinds of steroids you are talking about, how much, and for how long. Recreational steroids, so to speak, for bulking up, are probably not good for heart health. You can google that, too.
Interestingly, though, one recent study of medical steroid use after ablation for atril fib indicates that such use may help to prevent recurrence:
http://www.theheart.org/article/1139047.do
If you google steroids effect on the heart you may find your answer. Sorry I dont know the answer, but I have a feeling steroids would effect the heart, but thats a guess.