LAS VEGAS -- Dutch heavyweight Stefan (Skyscraper) Struve, slated to make a comeback Saturday after a heart scare, blacked out backstage and was scratched from his UFC 175 bout with Matt Mitrione.

"Stefan Struve suffered a non-life-threatening, near-fainting spell backstage," the UFC said in a statement. "Afterwards, the medical team did not feel he was fit to compete. With his health and safety in mind, he's been removed from the card and is currently under the care of the medical staff."

UFC president Dana White said Struve passed out while warming up. When he came to, he had an elevated heart rate. White said doctors initially thought it might be a panic attack.

The six-foot-11 Struve's MMA career appeared over last year when he was diagnosed with a rare heart condition.

Given the OK to resume fighting by his doctors in the Netherlands and the UFC's cardiologist, Struve (29-6) was looking forward to returning to the cage.

"It looks good," Struve said in a pre-fight interview, "I just need to do checkups two times a year with my doctors in Holland and two times a year with my doctors in L.A.

"That's no problem for me. I actually like that I know for sure that my heart is healthy."

The 26-year-old Struve, ranked 12th among heavyweight contenders, last fought in March 2013 when he suffered a broken jaw in a knockout loss to hard-hitting Mark Hunt in Japan.

He returned to training some three months later. But he blacked out briefly while at his parents' home and went to hospital to be checked out. A stress ultrasound test, which uses high frequency sound waves to examine the heart's anatomy and function, found the heart issue.

Struve was diagnosed with a leaking aortic valve, as well an enlarged heart. It meant that his heart was only pumping 60 per cent of his blood into the aorta and then the rest of his body. The remaining 40 per cent was ending up back in the heart chamber.

Doctors used medication to control his blood pressure and the demands on his heart. Struve says he will probably have to undergo surgery at some point but hopes to do it after his fighting career.