My point is that if he had long-term, undiagnosed heart issues that led to an enlarged heart with fluid around it, the vaccine may not have been the issue. It's rare, but young people can experience heart failure...hubby and I lost a friend while we were all in our early 30's who'd had a pacemaker put in during his early teens; and I have a friend who's infant has already undergone multiple heart surgeries - the first of which was not long after he was born. My step-father is considered to be in heart failure at this point...he regularly gets fluid around his heart...he's in his upper 70s.
I could be mistaken, but I've always been under the impression that in order for the heart to be enlarged, it has to have been working extra hard to do it's job over a period of time...not a matter of days.