The Poison front man, who has had a series of serious health issues in recent months, shared the mic Wednesday with "Idol" contestant Casey James, singing the hard rock band's hit "Every Rose Has Its Thorn."
"I didn't tell (my doctors) I was going to do this," Bret told MTV backstage. "But I feel great, I gotta be honest. There's still a lot of pain I'm still experiencing. (But) except for a little hitch (on) my left side from the ... stroke, I feel amazing."
Michaels, who won "Celebrity Apprentice," said he plans to have heart surgery this fall after he takes care of some of his other health issues. He has been undergoing treatment for a brain hemorrhage he suffered in April, which followed an emergency appendectomy.
Last week, Michaels, 47, was hospitalized again for what was classified as a warning stroke. While undergoing tests, he learned he had a hole in his heart. Doctors said he will be treated for his various health issues on an outpatient basis.
"I've spent the last month and a half in the hospital. I don't ever want to see a hospital again," Michaels said. "I just want to go out and have a great time."