At some point you will learn that you need to wear a bra 24/7 for the first several weeks after surgery. If you have larger breasts, like me, this is critical, because the weight of your breasts can pull on your incision and cause problems. 
The cardiac nurse told me ahead of time that any non-underwire front-closure bra would do, but this is not true. Thankfully, I had time to research this ahead of my surgery and I found this Judy longline bra from a company called Masthead Pink. They create post-surgical bras for both breast and cardiac surgery patients.
Something they don't tell you ahead of time — you will have surgical drain wounds.
Right below the incision which runs down the middle of my chest, I have two 1/2" scabs about 1/2" apart from each other where the surgical drains were removed. (Removing those drains tubes was not painful, but really weird-feeling, but that is a story for another time.)
When I try to wear a regular front-closure, non underwire bra, the bottom of the bra hits right there where those two scabs are. As I am writing this, I am 8 weeks post surgery, and I still have two pretty large scabs. Even when I unhook the bottom of the bra, it often rubs against them and was causing a little pain, and also resulted in one of the scabs 'leaking' a little bit.  I only wear the regular bra to work during the day, because it offers a little more support and lift than this surgical bra, but it's nowhere near as comfortable.
Because this bra is a longline, it doesn't rub there, and helps me feel protected and secure. It's really comfortable and easy to wear when you sleep. 
I ordered two of these so one can be in the wash when I am wearing the other one.
I ordered two of these so one can be in the wash when I am wearing the other one.
I ordered one in my measured size and one a size smaller.  The smaller one feels better now, but the larger one felt better early on.  When you wash them, be sure to close the velcro. I do that, but the velcro is still starting to fail a little. But then again, I have been wearing them for 8 weeks straight and am almost done with them.   
