The California State Athletic Commission has deemed former top welterweight contender Dan Hardy medically unfit to compete April 20 due to an irregular heartbeat, UFC revealed Thursday night.
"I couldn't be more disappointed," Hardy said on Twitter. "Turns out I have a wolf heart and the California commission won't clear me to fight."
Hardy (25-10 with 1 no-contest) was hoping to extend his win streak to three. After coming up short in his 170-pound title bout against champion Georges St-Pierre on March 27, 2010, Hardy dropped three fights in a row.
In his most recent outing on Sept. 29, Hardy defeated Amir Sadollah by unanimous decision.
Mien, 23, steps in fresh off an impressive first-round knockout of Dan Miller on March 16 at UFC 158. He is riding a three-fight win streak and has a professional record of 27-8.
Brown (16-11) has won his last four fights.