I had 4 plus years on an ortho/med-surg floor and then went to the ED. I had to take arrhythmia interpretation first, and once I was in the ED I had to take ACLS, PALS, and I just finished TNCC. I will do ENCP next year. I think it is definitely do-able without a tele background, but it would definitely be to your benefit to have tele. So much of the ED revolves around cardiac monitors! When I started orienting, I didn't even know how to turn the thing on, never mind change settings etc. But, it can be learned, it just might be a little harder for you early on. Just make sure you do your arrhythmia interpretation course FIRST, and know that stuff inside and out. It definitely helped me. Good luck!