He thanked viewers for voting for him and Buswell, adding he was “especially touched by the support from fellow heart patients”.
“I think perhaps I was too eager to impress them. They will know that recovery doesn’t always go in a straight line, and I hope they’re not too disappointed that I ran into the limits of my resilience much sooner than I’d hoped,” he said.
“I leave knowing that Strictly viewers are in very safe hands and I’ll be cheering for my brother and sister contestants all the way to Christmas.
“Despite this sad ending, it has been a genuine honour to be part of this huge, joyful and barking mad TV show. Long may it continue.”
During his time on the show Webb completed a tango, a cha cha and a quickstep.
Completed movie week
Last week he finished tenth on the judges’ movie week leaderboard with a score of 25 for his The Muppets-inspired dance, which he performed while dressed as Kermit The Frog.
Buswell said: “As a massive fan of Robert’s I was delighted to find out that he was joining the Strictly family.
“On top of this, to find out he was my partner was the icing on the cake.
“We made a great team, worked hard and had a good laugh along the way.
“I am so proud of the three amazing dances we produced. I know Robert had a lot more to give to the competition but his health of course comes first and I wish him a speedy recovery.
“I feel lucky to have danced with him and to call him a friend.”
Sarah James, Strictly Come Dancing executive producer, said: “Although we are so sad that Robert has withdrawn from the show we completely understand and support his decision, health always comes first.
“Despite their Strictly journey coming to an end earlier than anyone would have hoped, Robert and Dianne really made their mark on the competition, with three unforgettable dances choreographed superbly by the brilliant Dianne.
“They have been a wonderful partnership and we’d like to thank them for the commitment, creativity and joy they brought to the show.
“Everyone involved in Strictly Come Dancing sends Robert their love and best wishes for his continued recovery.”
Webb’s comedy partner David Mitchell called the news “sad”.
In a tweet, he added: “They did some really brilliant dancing, I thought. Sorry there won’t be more.
“And to those asking if I’ll be stepping in to replace him: I’m afraid not.
“I prefer to dance like nobody’s watching. And I can only do that if nobody’s watching.”