If your hospital recommends one, or offers one (some do, I guess) by all means give those a try. I purchased a vest type thing that velcro-ed up the front. Then I wore some of my husband's sleeveless ribbed undershirts underneath. So soft, those undershirts! Many of us are very sensitive for months around the sternum area. Also, the camisole tops with the lining (bra shelf) are excellent, though pulling them over your head may be a bit tricky for awhile (you may be stiff and achey).
Just also want to chime in that I am moving in a few weeks, downsizing dramatically and all the sorting and packing that goes with it. If I miss wishing you well before your surgery, please know that I will have you in my thoughts!! I know that you will keep the strength you need to get through this. You will be amazed at how much easier it is than you were (we all were) thinking!!
Godspeed!
Marguerite