Try checking in at Supertopo.com. Lot's of older guys over there, some of them are bound to have had open heart surgery. And some doctors too, who may have insight from both climber and physician perspective.
But whatever you do- do NOT ask Ammon McNeely. 89 days after a grrrruesome BASE crash, a WEEK after doctor telling him it was okay to put full weight on his rehabbing leg, he jumped again.http://www.supertopo.com/climbers-forum/2258496/Ammon-McNeely