Paul O'Grady's ITV early evening chat show was instead hosted by singer Michael Ball yesterday.
Presenter Stephen Mulhern said he had been brought in to front today's show, tweeting:
TV stars took to Twitter to wish O'Grady their best.
Phillip Schofield said:
Television presenter Paul O'Grady is in hospital after suffering an angina attack, a friend has said.
The 58-year-old comedian, who has had two heart attacks previously, told radio DJ Pete Price he was undergoing surgery today.
In a text message sent to Mr Price yesterday, he said: "I have had an angina attack and I will need a few days' rest.
"I am going to be out of the game for quite a while, and am going in for surgery tomorrow."
Mr Price told the Liverpool Echo that O'Grady had been overworking.
"When I saw he wasn't on TV I texted to ask what had happened and he told me about it. He is a total workaholic, and I have told him he needs to take things easy," he said.
Presenter Paul O'Grady is to return to teatime chat on ITV after more than seven years.
The comic has signed up for 25 shows initially to be screened later this year.
He had a similar slot for two years but quit in 2006, heading off to Channel 4 for a rival teatime show which he hosted for a further three years.O'Grady, 57, returned to ITV in 2010 and went on to present a Friday night programme for two series.
He won a National TV Award earlier this year for his programme For The Love of Dogs, with a second series starting soon.
His new hour-long studio based teatime show will air five nights a week with uests and music.
He said: "I can't wait to get back in the studio, it seems ages since I was sat behind that desk at teatime.
"I've missed all the fun and craziness of the show - and who knows, I might even get out my old organ?"
The programme will be made by O'Grady's own firm Olga Productions, named after one of his pet dogs.