Louis Walsh has said he fears for Nicholas McDonald’s health in this weekend’s X Factor final – revealing that he suffers from a rare heart condition which could be triggered by the stress of the show.

The Scottish teenager suffers from Long QT Syndrome, which caused him to suffer a near-fatal heart attack while playing in a football match at the age of eight.

And Louis has now told The Sun that he is worried Saturday’s show will prove too much.

“I am worried about the stress and strain on Nicholas,” he admitted. “He has this serious heart condition. I worry about that for the weekend, honestly.

“There is nothing we can do. He is working really hard — we are just going to give him some time off,” Louis added. “I think his family are worried but we want him there in the final.”

Nicholas explained that the condition causes an irregular heartbeat, and that he has to take daily medication to control his heart rate.

“It’s weird to think my heart could stop and I could just die tomorrow,” he confessed.

“But that’s why I live every day as much as I can and enjoy it.”

An X Factor spokesman said that producers had paid for Nicholas to have a private medical before the live finals started to ensure he could cope with the pressure.

“There is a team of medics here, as there is at all shows, so they will monitor Nicholas,” the spokesman added.

Meanwhile the 17-year-old – who will duet with Westlife’s Shane Filan on Saturday night – tipped singing prison officer Sam Bailey for the series crown.

“Sam is the one to beat, I’ll admit it,” he said. “But I think everybody’s got a chance.”

The action kicks off on ITV at 8pm.