Rugby great's heart surgery after 'miracle' discovery

New Zealand rugby great Sonny Bill Williams has revealed he's had successful open-heart surgery at the Royal Melbourne Hospital.

In a long video documenting the health issue on his YouTube channel, the 41-year-old Williams said he discovered he had been born with a heart defect after going for a routine check-up following a neck operation.

In footage taken after heart surgery, the Sydney-based Williams said it was a success and that he was making it his "mission" to raise awareness of the need to take heart checks.

"It's the hardest thing I've ever done. Day two, honestly, I thought I wasn't going to make it. It was crazy," the father of five said.

Williams started out as a rugby league player, becoming a superstar in the 13-man code, before switching to 15-man rugby union and winning the World Cup twice with the All Blacks, in 2011 and 2015.

He retired from both rugby codes in 2021 and has since taken up professional boxing, his most recent heavyweight fight coming last year.

Williams said doctors told him that having a heart defect would have affected his sporting career.

"Upon reflecting, I feel like toward my late 20s, I definitely felt like I couldn't get as fit as I used to," he said.

"The doctors both said it is a miracle that you found it because it's a case of a perfectly fit-looking person dropping dead."

Speaking from inside the hospital, Williams said he has a "better heart than when I walked in here."