Arnold Schwarzenegger has reportedly undergone emergency heart surgery.

The 70-year-old Hollywood legend is believed to have required emergency open-heart surgery after he visited Cedars-Sinai Thursday (29.03.18) for a catheter valve replacement, where he developed complications.

According to TMZ, the valve replacement was an experimental surgery, and doctors were prepared incase the procedure failed.

The outlet claims they quickly decided Arnold needed emergency open-heart surgery, which allegedly lasted several hours.

As of the time of writing, the 'Terminator' star and his family - including ex-wife Maria Shriver and their children Katherine, 28, Christina, 26, Patrick, 24, and Christopher, 20 - have not commented on the news.

It isn't the first time the star has gone under the knife for important surgery, as in 1997, he underwent elective heart surgery in Mexico to replace an aortic valve.

Speaking in a statement at the time, he said: ''I've never felt sick or had any symptoms at all, but I knew I'd have to take care of this condition sooner or later. I said to the doctors, 'Let's do it now, while I'm young and healthy.' They agreed this was the way to go.''

The news of his surgery comes after Arnold recently revealed he doesn't feel his age, and is still working hard and enjoying a ''great'' life.

He said: ''I feel the same way [now at 70] as I did 20 years ago.

''It's only on my passport or my driver's licence, but I feel the same way as I did 20 years ago.

''I feel good about myself. I work out. I make my movies. Life is great. I feel useful and productive.''

The 'Predator' star also claimed he still has early morning workouts every day, where he pushes himself as hard as ever.

He revealed: ''I lift all the time, I go every day to the gym. I bicycle, I lift, I ski, I do everything else.

''I get up at 5am and I ride the bike to the gym. I work out there for an hour, then I ride home and have breakfast.

''My day starts like that. Before I ever get to the office, I've already done my workout for the day. I've done something.''