Does anyone know if this could permanently worsen my ME/CFS?
I am not qualified to answer that exact question, but I did want to share with you that I had an IV chemical injection stress test in 2014. I was quite ill (in hospital) at the time so declining the test wasn't really an option.
I don't feel like it did any major harm to my overall condition, but I was completely wiped out afterward as well as the entire next day. It's like your heart goes out for a 10-12 minute jog while you lay still on a hospital gurney. It was a pretty yucky sensation, for me, but I had a nice nurse tell me to concentrate on breathing deeply and curling my toes as a distraction.
Again, I'm not a doctor, so I can't say if undergoing such a test will permanently worsen your condition, but I would suggest that if you do go forward with the test that you mentally prepare yourself for a crash of some sort.
Hopefully others who have undergone this type of test will contribute their thoughts as well.
I wish you the best of luck! It's not easy to make these types of decisions.