Imperial Commander was sixth favourite to regain the crown he won in 2010 when jockey Paddy Brennan steered him to victory over the two favourites Denman and Kauto Star.
The 12-year-old could return for the Grand National meeting at Aintree in April.
Trainer Nigel Twiston-Davies said: "He's got a lung infection so he won't be going to Cheltenham, that's that. What can you do, it's an absolute sickener but they are very delicate creatures.
"I'm sure he's still as good as ever, he's been in great form, but you can't rush them. Hopefully, he'll be OK for Liverpool."