Giles' manager, Oren Hodak, told ESPN that Giles seemed fine afterward but was taken to the hospital for precautionary reasons. Giles was released on Sunday afternoon, Hodak said, and plans to fly back to Houston on Sunday night.
In an Instagram post Sunday, Giles said "heart irregularities" might have led to his fainting spell.
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Got held over night in the hospital. Apparently I have heart irregularities that may be the cause of all this. Just had a heart cardiogram this morning. Waiting for the good news and back to Houston I go. I will enjoy my family, assure all my loved ones that I'm okay, then I will prepare to handle some unfinished business. Thanks for all the love and concern.
The contest was scheduled to start the main card of UFC Fight Night: Brunson vs. Shabazyan. The event took place in Las Vegas at the UFC Apex, the promotion's facility across the street from its corporate campus.
UFC president Dana White said UFC attempted to get Ed Herman to fight Holland at the 11th hour. Herman's opponent, Gerald Meerschaert, withdrew earlier Saturday due to a positive coronavirus test. But Herman had already left the UFC Apex and was unavailable to return for the card, White said. Holland could fight on the UFC card Aug. 8, per White.
"Holland could not have had a better attitude," White said. "... I'm excited to see him come back and fight."
Giles (12-2) was coming off a split decision win over James Krause at UFC 247 in February. The 27-year-old Texas native is an officer for the Houston Police Department.
Holland (17-5), also a 27-year-old Texan, most recently beat Anthony Hernandez by 39-second TKO in May.
Calderwood's manager, Danny Rubenstein, confirmed to ESPN's Ariel Helwani that she fainted as she was getting checked out in the medical room. He said that John Wood, Calderwood's head coach and fiancé, caught her and that they laid her down and carted her out on a stretcher.
Rubenstein told Helwani that Calderwood's "heart rate dropped on the way there" but stabilized. Calderwood was discharged from the hospital late Saturday night and is at home resting, Rubenstein said.
It was unknown what caused Calderwood to faint.