New York Islanders defenseman Mike Reilly will undergo a heart procedure on Tuesday that will sideline him indefinitely, the team announced Monday.

Reilly didn’t know he had a heart condition until it was found during testing for a concussion that he sustained during a 4-3 victory over the Buffalo Sabres on Nov. 1. He landed on injured reserve because of that concussion and has missed New York’s past seven games.

“It was picked up through the different echocardiograms that you do for different reasons that you go through with any post-concussion situation,” Islanders general manager Lou Lamoriello said of the heart problem. “It’s probably a blessing in disguise of what transpired. They detected this, something that you’re sometimes born with but never knew.”

Lamoriello said it could be “several months” before Reilly is back on the ice.

“(His quality of life will be) 100 percent, and he will be able to play once this procedure is done,” Lamoriello said. “It takes quite a bit of time.”

Reilly, 31, has not recorded any points in 11 games this season for New York.