Struve, who had previously been sidelined after doctors discovered a bicuspid aortic valve, was set to face Matt Mitrione in a heavyweight bout on the pay per view undercard of UFC 175, but passed out in the locker room. The fight has now been scratched.
UFC president Dana White has been manning the ESPN SportsCenter Twitter account and sent out a tweet confirming the news just moments after it began picking up steam from media members, "Stefan Struve blacked out in the locker room. He has elevated heart rate and is out of the fight. I'd never risk his health."
The main card will now be four fights, the broadcast will likely use a prelim fight from the Fox Sports 1 or Fight Pass broadcast to fill time to not throw the fighters off schedule.
Update: Multiple reports from media members on site state that Dana White said the doctors believe he had a panic attack, but they didn't want to take any risks with his health.
Update 2: The UFC has classified the situation as a "near-feinting spell." They have also stated that he is in fine condition now but the fight will not take place.