Kevin Smith was told by his doctor that smoking marijuana before his heart attack ''saved his life''.

The 47-year-old director and comedian underwent emergency surgery in February after being taken ill between stand-up shows, and has revealed that thanks to having smoked the drug earlier in the day, he remained calm in the emergency room, which doctor's say is what saved his life.

He said: ''They got me to the hospital and they wheel me into the emergency room and the whole time I'm chill. Like, the guy said, the paramedic he goes, 'You're being real calm, that's going to get you through this'. And there's a dude behind him goes, 'That's what's going to save his life.' And I'm like, 'What does that part [mean]?'''

Kevin told the doctors at the hospital that he had smoked ''too much weed'' because he thought that the drug had caused the health scare, but was told that it had instead stopped his ''massive heart attack'' from killing him.

Speaking during an appearance on 'The Late Show with Stephen Colbert' on Tuesday (01.05.18), he said: ''I said, 'Doc, honestly, I just smoked too much weed this morning. That's what this is'. I honestly thought I was too high. I'd smoked a bunch of weed that day because I was doing the show and then I smoked a joint right before the show and then I got off stage and all of the sudden I had a heart attack.

''He goes, 'No, quite the opposite. That weed saved your life.' And I was like, 'Do tell! Like, what do you mean?' He said, 'You kept calm. They told you [that] you were having a massive heart attack, and you remained calm the whole time, so that joint saved your life.'''

Previously, the 'Clerks' helmer had claimed he didn't even know he was suffering from a heart attack until he was undergoing surgery, and said smoking a joint had stopped him from feeling pain.

He said: ''I didn't know, until I was in the hospital room, that I had a heart attack.

''[The doctor] was like, you've had a massive heart attack, and I was like, 'Nobody told me, are you serious?'

''And he's like, 'what's your pain threshold on a 0-10?' I was like '-3.' He was like 'Are you high?' I said, 'Yeah I got blazed before my show, maybe that's why I feel no pain.' ''