if you are worried definitely give them a call, they won't mind answering your questions, or even getting you to come in and be monitored. As Berenice said, I'm sure they'd much rather it be a false alarm and go through all the tests as a precaution, than it being worst case scenario... And I think you need to put your mind at ease too, no point worrying about it until your appointment, which could possibly make it worse! hope everything is ok