Roger,
I had both done with an EF of 10%. The stress test had to be stopped before completion, but it and the cath gave my medical team the necessary info needed to treat me.
While there are risks associated with nearly everything, I think the benefit you'll receive from the tests outweigh the risks. Of course, since you're uneasy, you need to discuss it further with your doctors or get a second (or even third) opinion.