I have cardiomyopathy, but it is from chemo, not radiation. Did you have chemo? My cardiologist said that he did a study when he was getting his degree on the affects of adriamycin on the heart, and they can be great.
Your echo will give them a good picture of how things are. I have been on Coreg for a year now and just had another Echo done this week. Will soon know if the meds are doing what the Dr feels they will do. He told me that chemo induced cardiomyopathy can be reversed. Let's hope so.
If you have any other questions about it, don't hesitate to ask.
Take care and God Bless - meantime, get as much rest as you can.