The aftermath of this will be very interesting. Heart surgery can cause postoperative mental confusion that lasts for months or sometimes years. My father-in-law had triple bypass surgery last October, and following surgery he was confused, forgetful, disoriented, and cantankerous for a long time (and still isn't fully back to normal, mentally), and this has caused quite a problem for my mother-in-law. His thoracic surgeon says this is pretty common, and warned us before the surgery that this might happen.
Clinton might make some pretty weird speeches later on if he suffers such postoperative confusion.
I'm no expert, but I've seen this several times and I believe it is a side effect of the meds. I say this because sometimes people "forget" their meds and wake up for a while.