Back in 2015, a man decided to take out his camera and film the 'strange' symptoms he was experiencing - harrowingly he had no idea he was actually having a heart attack.
Alain Bruno shared the footage of the heart attack taking hold of his body when he uploaded video clip to YouTube, having decided to film himself as he experienced a number of symptoms including chest pain and breathlessness.
Pre-warning viewers to what they would see, Bruno captioned the video: "It's the scariest thing that ever happened to me. Today while practising for a new video, those symptoms proved to be a heart attack.
"I was in pain and I panicked. I thought I was dying.
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"Luckily my roommate came home early and immediately called 911.
"I am ok now but I have to be careful for the rest of my life because heart disease runs in my family. Stay safe!"
The footage might be over nine years old but it remains just as scary, with Bruno seen talking before struggling to speak and clutching at his chest.
The video continues as he's clearly in severe pain, which then eventually worsens to the point where he doubles over in agony, clutching onto his chest.
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The video has had many comments over the years, with some viewers hoping we can all learn from Bruno's experience.
One person commented: "This is a perfect example of why you should never be afraid to call 911 when you are experiencing feelings that don’t feel right.
"This poor guy could have been 60 seconds away from dying."
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Another shared: "He's so young and fit. Terrifying that this could happen at any moment to anyone."
A third shared: "The worst part is... Is that if he were to have passed out from the pain, he probably would have drowned."
A fourth posted: "Thank you for posting this scary but informative experience.
"They always tell you the symptoms to watch out for but It really helps to see it actually happening and what it really looks like."
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NHS guidance for heart attacks suggest symptoms aren't always just severe chest pain.
The website reads: "While the most common symptom is chest pain, symptoms can vary from person to person.
"Some people may have other symptoms such as shortness of breath, feeling or being sick and back or jaw pain without any chest pain."
The health body also advise: "Call 999 immediately if you think someone might be having a heart attack. The faster you act, the better their chances."
Niamh Spence