The rocker and reality TV star's website reports that Michaels suffered what doctors call a "warning stroke" and has been diagnosed with a patent forum ovale, or hole in the heart. Michaels' publicist, Joann Mignano, confirmed the report.
The condition is operable and treatable but likely unrelated to the brain hemorrhage the 47-year-old suffered last month.
The website says Michaels is "up, walking, talking, continuing his daily rehab and very happy to be alive," and hopes to make a full recovery.
The Poison frontman was expected to appear at Sunday's finale of "The Celebrity Apprentice" in New York.