I'm a bit puzzled about this. Not exactly sure what your doctor meant by "extra beats" and what's he's trying to determine with the nuclear stress test exactly. Why were you in for the stress test, EKG, echo, etc. in the first place?
If the (non-nuclear) stress test was inconclusive it would be normal procedure to go to the nuclear stress test, I believe. I do not see any direct relationship between the "extra beats" and the doctor calling for a nuclear stress test.