Jason Byrne has told RTÉ Radio 1's Ray D'Arcy Show of his shock at discovering that he needed "five stents put into my arteries", urging people to have their cholesterol checked and to visit their doctor if they experience any chest pain.
The 49-year-old comedian said he had been "very lucky".
"I'm a runner, like the way you're a runner," he told the host. "I cycle, I walk, I have a good diet. And I was on Portmarnock beach and I went for a run and I felt a pain in my left side like a kind of a bit of pressure - and that didn't feel right.
"So I went straight to the doctor, straight to [cardiologist] Rory O'Hanlon there in [the] Blackrock Clinic. He did tests on me, and then eventually I needed five stents put into my arteries."
When asked to describe the pain, Byrne replied: "I didn't have a heart attack. It's almost like if somebody got their finger and kind of pushed it on your chest, do you know what I mean? Kind of pushed it in."
"And whereabouts on your chest?" asked D'Arcy.
"On my left side, like right at my heart," Byrne explained. "If you have your heart, just go to the right of my heart. And so it wasn't my main arteries; there's arteries off the side of your heart.
"What happens is cholesterol was building up in three different arteries, and that was happening over many years. I didn't know that because it's all hereditary - this is where it all came from."
"So the pain I felt, it was just... Because I was training and I was running hard, the blood was trying to get through a very tight area and it just couldn't get through there," he told D'Arcy.
"It was like a feeling of just a pressure. My breathing was fine. I didn't feel faint. I didn't have any kind of... because people ask me, 'Did you feel this before in any other day?' No other day did I feel this.
"I said [to the doctor], 'Well look, I might as well go and have burgers and chips now and smoke cigarettes and drink because I never did any of that'. But he said, 'No. Because you were exercising, you got your heart rate up and that helped keep the cholesterol [down]. Even though you made a lot of cholesterol, that still helped push it down'.
"He said, 'Because your heart rate went up, you felt that pain before you would've had a heart attack. If you were sitting at home doing no exercise or no walking or no movement, that cholesterol would've built up on its own'. And then I would've hit the deck, do you know what I mean? No warning."
Byrne said there is a history of heart issues in his family.
"I didn't have any high blood pressure. My cholesterol was a bit high - and they were a bit concerned with that - but they still couldn't get [find] the pain. The only thing that really sorted it out was the scan, was an angiogram.
"The main thing he [the doctor] said was people like me are the very people that don't get checked out, Ray. So why would I get my cholesterol checked? I run everywhere, I'm fine. I gig all the time. I move. And he goes, 'But it's people that have mams and dads or anybody in your family [with cholesterol issues] that need to get checked'. Because we don't know it's building up inside us. We just have no idea."
Byrne is now back on tour - and enjoying life again.
"I always did kind of appreciate life, but I really do now," he said. "It's so fragile, life is. And when you're given this kind of a chance... I know we're going through the Covid and all that kind of thing, but my God - just to be alive is fantastic."
