You Must Know Me had to be put down after making all the running in the Leopardstown Inn Hunters Chase at the Dublin track.
The 10-year-old was reported to have broken a leg just as he was passing the winning post clear of the opposition.
His rider Barry O'Neill was able to dismount as soon as they had crossed the line.
It was a sad postscript as You Must Know Me (9-1) had led the field a merry dance. Leading from the start, only Anseanachai Cliste tried to go with him.
When he had had enough, David Christie's runner was left to win unchallenged.
It Came To Pass got within a length and three-quarters with Salsify four and a quarter lengths away in third.
Enda Bolger's even-money favourite On The Fringe, having his first race since winning at Punchestown in early May, was only seventh.
Bolger said: "I'm a bit disappointed. I was hoping for a bit better, but at least we still have our horse.
"It's terrible luck on the connections of the winner."