Popular YouTuber Alex Dragomir, also known as Sir Kipsta, has died at the age of 17 following an operation.
Alex's sister confirmed his death via his Twitter account on Friday (local time).
“He had a very hard operation which lasted seven hours but his heart couldn’t take it anymore, he was too weak to survive,” she tweeted.
“Heaven gained another angel. He was my rock, my everything. RIP Alex.”
Alex tweeted the day before he was going in “for a life saving procedure”.
"If it don't work, then it's been a great time people,” he tweeted.
"Thank you for all you've done for me."
The teen, known for posting videos about his football team, Manchester United, had more than 27,000 YouTube subscribers. He also posted videos about his struggles with his heart condition.
His last video, filmed from hospital, received more than 38,000 views.
A GoFundMe page had requested donations so Alex could get a heart transplant.
Alex often kept a positive attitude while dealing with his heart condition.
Just days before he died, he tweeted: “Positivity is the way forward."
He was also remembered by players of his football team.
Manchester United forward Marcus Rashford tweeted his heartbreak over news of Alex’s death after the teen tweeted he had been reading the player’s book.
“My guy,” Rashford tweeted.
"I hope this book brought you at least a little enjoyment at the end.
"What an absolute superstar, fought until the very end. I was always thankful for your support."
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