Bobby, I had triple bypass surgery on Oct.2 '08.
First two weeks, my sternum had quite a litle "snap, crackle, & pop" until things started to mend. I followed the surgeon's directions about not lifting too much, balancing loads, etc. At six weeks, I was given the OK to "try whatever you want; your body will tell you when it's too much" I shot a 35# bow for a week, 45# for a couple days, and went hunting for the first time with a 50# bow at 8 weeks. I am now shooting 60-70# bows daily, and had a great 6 month checkup.
I followed cardiac rehab religiously for 8 weeks, until I was released to go back to work...and I've followed a daily regimen of exercise since...
I think a lot of it depends on your commitment to getting yourself back up and at it...I've heard from a number of open-chest surgery patients who have said it was over a year before they felt healthy enough to pull a bow...for me, that wasn't acceptable...
Good luck!
Kevin