"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," Smith said on the Late Show. "Then I got off stage and all of a sudden I had a heart attack. I asked my doctor after this was all done, I was like, 'I hate to ask this question, man, but did I have a heart attack because of the weed? Because I smoked a joint right before the show.'"