Baffled by Sudden Death

[TeriNick50]

I found "Big Red" dead in the coop.
She was only 4 yrs old.
It looks like she laid an egg, got out of the nesting box and died.
Is it possible she had a heart attack?
I am baffled as this hen seemed very healthy.

 

[crested1990]

passing the egg could have caused internal damage if it was too big.