It is well known that when Christian Bale is cast in a film, he gives much more than your run of the mill actor. He fiercely devotes himself to perfecting the role, learning the tiny nuances of characters and even transforming himself physically.
For his role in Vice, in which he plays former US vice president, Dick Cheney, Bale put on 3st 4lbs. But it was his study of heart attack symptoms which has proven to be more significant still.
Cheney famously suffers with cardiovascular disease, having had his first of five heart attacks when he was only 37, before going on to eventually have a heart transplant aged 71. In order to convey these heart attacks accurately, Bale researched the symptoms - not knowing what a huge impact this would later have on the life of director, Adam McKay.
Ironically, the director suffered a heart attack of his own in January and says if it weren't for a conversation on set with Bale, he may have lost his life.
Speaking to Deadline, 50-year-old McKay said: "We finish the movie and I call my trainer. I say, we got to get on it, man. I'm too heavy.
"Our third workout, I get tingly hands and my stomach starts going queasy. I always thought when you get a heart attack, it's pain in the chest or the arm.
"But then I remembered, when we shot one of the heart attack scenes, Christian Bale asked me, 'How do you want me to do it?' And I go, 'What do you mean? It's a heart attack. Your arm hurts, right?'
"He says, 'No, no. One of the more common ways is that you get really queasy and your stomach hurts.' I said, 'Really?' I'd never heard that before.
"And right in that moment [when McKay doubled over] I went, 'Oh shit,' and I ran upstairs and downed a bunch of baby aspirin, and I called my wife who immediately called 911. Got to the hospital really fast, and the doctor said, because you did that, no damage was done, your heart is still really strong.
"That's because I remembered Christian Bale telling me that. The doctor said, you got to quit smoking, that's what's doing this to you. You need to lose weight, but the smoking's making it four times worse.
"I called Christian a week later and said, either you or Dick Cheney just saved my life."
The very definition of a life-saving performance from Bale there.
McKay was able to take some positives from the situation though, making an unexpected cameo by using an image of his heart attack in one of the scenes in the film.
Fortunately for McKay, none of the themes from his comedy classic, Anchorman, were mirrored in his personal life.
Vice is released on Christmas Day in the US and on 25 January in the UK.
Featured Image Credit: PA/Annapurna Pictures