Jacksonville Jaguars defensive lineman Rodney Gunter is retiring after revealing he has a serious and potentially life-threatening heart condition.
The 28-year-old, who signed a three-year deal $18m contract with the Jaguars in March, made the announcement on Sunday.
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Gunter previously played five seasons with the Arizona Cardinals, starting a career-high 13 games in 2019.
"These last three weeks have been a hard pill to swallow," Gunter said on Twitter.
"Seeing my dreams vanish right in front of me has been extremely difficult.
"After seeing several heart specialists I was told if I continue to play ball with my condition, I could possibly rupture or tear my aorta which is enlarged. This can cause sudden death or a severe stroke.
"There is a 50/50 chance that surgery will fix my current health condition. But at the moment, I do not meet the criteria to undergo the operation.
"Those who qualify must have 5.5+ cm enlarged aorta, while mine measures 5.0 cm. At this time, I cannot play or have the surgery so I must wait.
"So at this moment, the best choice for me and my family is to walk away from this game.
"I appreciate the Jaguars for giving me an opportunity, and I'm thankful for everyone who has believed in me along the way. Thank you!"
Gunter was placed on the active/non-football illness list to begin Jacksonville's training camp.
He registered 126 tackles, 26 tackles for a loss and 11 sacks in Arizona, who drafted him in the fourth round of the 2015 draft out of Delaware State.