The horse, a 25-1 shot, is the first Grand National horse to be put down since 2012.
General Principle also fell a but is reported to be fine.
-> Deer killed and butchered in Hawksworth Wood LeedsAll other 38 horses finished the race safely after being checked over by vets.
Tiger Roll raced into the history books to become the first horse since Red Rum to win back-to-back Grand Nationals.
Trained by Gordon Elliott, Tiger Roll appeared to hold outstanding claims of claiming a second victory on Merseyside, having looked better than ever in winning his two most recent starts in the Boyne Hurdle at Navan and the Glenfarclas Cross Country Chase - his fourth Cheltenham Festival win.
Davy Russell had the 4-1 favourite well positioned throughout the four-and-a-quarter-mile journey and after moving to the front, he found plenty on the long run-in to claim an historic victory over 66-1 chance Magic Of Light.
-> Driver and passengers flee after car crashes into Leeds prisonRathvinden (8-1) was third, with Walk In The Mill (25-1) fourth.
Winning owner Michael O'Leary said: "It's unbelievable. It's a phenomenal training performance by Gordon. It's brilliant that he keeps bringing this horse back at Cheltenham better than ever and Aintree better than ever.
"And what a ride by Davy - fantastic. It's unbelievable, to win two Grand Nationals is just incredible.
"It's a great result for the punters as well."