METAIRIE, La. — Saints defensive tackle Nick Fairley is coming off one of his best N.F.L. seasons, and it might have been his last.

At the very least, he will not be playing for New Orleans in 2017.

General Manager Mickey Loomis said Monday that Fairley has been placed on the team’s injured reserve list with a nonfootball-illness designation, meaning Fairley is out for this season.

The 6-foot-4, 308-pound Fairley had a career-best six and a half sacks for the Saints as a starter last season, after which he signed a four-year extension worth up to $28 million.

However, symptoms related to an enlarged heart caused Fairley to miss off-season practices and minicamp while he saw specialists to determine whether playing football would be an undue health risk.

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Saints Coach Sean Payton said at least one specialist had recommended that the 29-year-old Fairley — a former Auburn star and a 2011 first-round draft pick by Detroit — give up football. Payton had also mentioned that he wanted to be sure Fairley would not return unless he was confident enough in his health to play to his full potential.

“The most important thing right now in our mind is his well-being,” Payton said this month, when Fairley’s status for this season was still in doubt.

“To play this game, there’s a little bit of mental toughness involved, obviously. I want to make sure, if in fact he’s playing it, again that he’s playing with full confidence that he’s healthy to play and that nothing severe would come of him playing.”

The Saints’ move Monday sidelined Fairley for only 2017; his future beyond that remains unclear. He has been playing his whole N.F.L. career with an enlarged heart, which can be caused by health problems of varying severity.