Pig heart attacks?

Can pigs die of a heart attack due to being overweight?  If so, I think ours might be close.  They're so heavy it takes all their energy just to move from the hut to their food bowl (to eat and get fatter).  I think we really need to butcher them soon, but it's rained just about every weekend for the past few weeks.  I'm not even entirely sure how we will butcher these two.  They have to weigh every bit of 300 lbs.  It will probably take 3-4 of us to hoist them up.  Dunno.  I'll just cross my fingers that they don't have a heart attack in the meantime.