That's good news! If they want you to take a stress test, they must think that you're in pretty good shape.
Sure, every doc hopes his patients will live a while longer.
But if they schedule you to run to exhaustion IN THEIR OWN LAB, then they are TOTALLY SURE that you're not going to die that day no matter how hard you push.
And their lawyers are sure, and their insurance company is sure.
What could be more reassuring?