Update: On April 2, Arnold returned to Twitter to give fans an update on his health condition after he underwent emergency heart surgery on March 30.

It's true: I'm back! I went to sleep expecting to wake up with a small incision and woke up with a big one - but guess what? I woke up, and that's something to be thankful for. Thank you to the doctors & nurses. And I'm truly filled with gratitude for all of the kind messages.

— Arnold (@Schwarzenegger) April 2, 2018 [1]

Original Post: Arnold Schwarzenegger has undergone emergency heart surgery [2], TMZ reports. The actor went through with a scheduled surgery for a catheter valve replacement at Cedars-Sinai Medical Center in Los Angeles on Thursday and experienced complications when the replacement failed. Doctors then performed emergency open-heart surgery. According to sources, Arnold is reportedly in stable condition.

The Terminator star previously had heart surgery in 1977 [3] to replace an aortic valve. "I've never felt sick or had any symptoms at all, but I knew I'd have to take care of this condition [4] sooner or later," Arnold previously told the Los Angeles Times. We wish Arnold a speedy recovery.