Plenty of my family members have had open heart surgery, all with 100% success. It's has come a very long way in the past 20 years. She should do fine, but must follow the post-surgical recovery instructions, diet, take her medications, etc.

I must warn you, so that you are prepared: Sh might look very good right after surgery, and may complain a lot, but this is normal even with much younger patients. They'll probably have her up and about fast, though.

Best wishes