Director Kevin Smith is lucky to be alive after suffering a so-called "widow-maker" heart attack at just 47 years old.
The heart attack occurs when the left anterior descending artery is completely blocked.
"It blocks off blood supply to the heart," Dr. Mehmet Oz, of The Dr. Oz Show, told Inside Edition. If it happens, "there's no plan B," he said.
Smith, who is best known for films like Clerks and Dogma, sought immediate medical attention after feeling nauseous at the Alex Theater in California, where he was performing a couple of stand-up shows.
"I started sweating buckets and my chest felt heavy," he wrote in a lengthy Facebook post. "If I hadn't canceled the second show to go to hospital, the doc said I would have died."
Dr. Oz said the "classic symptoms" include shortness of breath, sweating, nausea, chest pains and heart palpitations.
"Your heart thinks you're running a marathon if you're just standing still," Dr. Oz said.
He advised immediately calling 911 or getting someone to take you to the emergency room if that's quicker. You should also take an aspirin of any size and chew it at the first sign of symptoms.
Smith's father died of a heart attack in 2003, and after his own health scare, he said, "Maybe it's time to go vegan."