Tricia,

My Father started to have heart issues at 43 in 1973. He had one of the first triple bypass operations in the country.He and we always thought he was going to die every year. Actually would go through this whole "I don't think I'll be around much longer.
When he died at 66 in 1998, we almost put "I told you I was sick" on his tombstone.
The point is that regardless of what anyone tells you, you are in the best country in the world for health care. Most people come through things fine. I am sure your sister will as well. Try not to get too worried. Just take it as it comes and have a great attitude. It is especially important for your sister to get strength from you.

Good luck and remember a lot of people are pulling for you.

MAB