Doctor nurse help with heart condition SVT?

Im diagnosed with AV node supra ventricular tachycardia.I have a few questions... Is my condition deadly? Im a competitive cheer leader and i get worked out till i cant move another muscle and usually when im working out i don't have pain in my chest but it fells like my hearts stopping and for few seconds whats going on there? Im on a medication for is Lynxion i think... and i forgot to bring it on my vacation and didn't take it should i start up again on it? ( i didn't have any episode without the medicine)