The news was announced today by Newport County, where he was named club captain last August.
NEWPORT COUNTY HAVE announced the retirement of their Irish defender Mark O’Brien.
The League Two club revealed today that the 27-year-old Dubliner has been forced to bring a premature end to his playing career as he requires heart surgery.
“The club will be doing everything it can to support Mark at this difficult time,” the Welsh outfit said in a statement.
Having joined Newport from Luton Town in 2017, O’Brien made 127 appearances in all competitions. He was also appointed club captain last August.
He began his professional career at Derby County, where a heart issue was first detected during a routine medical check when he was 16. O’Brien, who subsequently underwent surgery, played 204 games during his professional career.
“They found a minor leak in the aorta valve,” he explained during a 2016 interview with The42. “We thought it was nothing too serious at first. Initially the doctor told me I wouldn’t need an operation for 20 or 30 years.
“Our heart rates were continuously being measured at training, but they found that my maximum heart rate was becoming really, really high. It started getting a lot worse.
“I went for an MRI and they found the leak was escalating faster. And then suddenly, I was told I needed an operation within the next two weeks, otherwise I could drop dead on the pitch.”
Last year, O’Brien captained Newport to the League Two play-off final at Wembley, where they suffered a 1-0 defeat to Tranmere Rovers. He also played in their memorable FA Cup upset wins over Leicester City and Middlesbrough.
On the final day of the 2016-17 season, his 89th-minute winning goal against Notts County prevented Newport from being relegated from the Football League.
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