I would do like @dmk suggests. Since you have such tight time constraints, you should do some polite pushing from your end pointing out the timing problems and having to delay or cancel the surgery if all the required tests don't get done. It's possible the RN was over diligent in insisting on the stress test, since the cardiologist never mentioned one, or maybe she is right and he just forgot. This needs to be cleared up quickly, and only you have the power to push for an answer from your cardiologist. They do have many patients, and despite best intentions, sometimes paperwork/data gets put aside to deal with other critical cases and they may not realize your urgency until you call them.