Minnesota Vikings backup linebacker Cameron Smith, who underwent open-heart surgery last year, has "made the difficult decision to retire from the NFL," according to an Instagram post he wrote Wednesday night.

Smith, 24, had surgery to repair an enlarged heart last August after a false-positive COVID-19 test led to the diagnosis of a genetic defect. He missed the 2020 season but was set to resume his career in 2021.

Smith played a few snaps in Minnesota's preseason opener on Saturday before departing in the second quarter with a concussion.

"For the past 18 years, football has been such a tremendous part of my life," Smith wrote in the post. "It has provided countless friendships, incredible memories, and invaluable lessons that will last a lifetime. When I had open heart surgery last year, I grappled a lot with what I had been asking my body to do in order to play this great game. Ultimately, I've decided that I've been asking for it to do too much.

"After careful consideration and thorough discussion with my friends and family, I have made the difficult decision to retire from the NFL. I know this transition isn't going to be easy, but I am excited to tackle this next chapter of my life with the same passion and pursuit that I did football."

Drafted by the Vikings in the fifth round out of USC in 2019, Smith wrote that he will "forever cherish" the many opportunities that he has been given through football.