Mike Reilly will be out indefinitely as the defenseman will undergo a procedure on Tuesday to address a preexisting, but previously uncovered heart condition, Islanders President of Hockey Ops and General Manager Lou Lamoriello announced on Monday afternoon.

Lamoriello said the issue was found during routine tests after Reilly’s concussion on Nov. 1 in Buffalo. The condition is unrelated to the hit, and subsequent injury, Reilly suffered in Buffalo. Lamoriello also said Reilly has been cleared from the concussion.

“It was picked up through the different echocardiograms that you do for different reasons that you go through with any post-concussion situation,” Lamoriello said.

While the hit was obviously scary in the moment, Lamoriello said the silver lining was finding this previously unknown issue.

“It’s probably a blessing in disguise of what transpired,” Lamoriello added. “They detected this, something that you’re sometimes born with, but never knew.”

While Monday’s update means the Islanders will be without their defenseman for the foreseeable future, Reilly’s long-term health is the priority and the 31-year-old is expected to be able to continue his hockey career after the procedure, but there is no definitive timeline for a return.

“[His quality of life will be] 100% and he will be able to play once this procedure is done,” Lamoriello said. “It takes quite a bit of time. It could be several months before he’s back, because of the type of procedure.”

Reilly has three hits and four blocked shots through 11 games this season.

UPDATES ON BARZAL, DUCLAIR, PELECH AND ROMANOV

Lamoriello also provided updates on the Islanders other injured players.

Alexander Romanov is still considered day-to-day and is a “game-time decision” for Tuesday, per Head Coach Patrick Roy. Romanov skated was a full participant in his second straight practice on Monday.

Anthony Duclair has not resumed skating yet, but Lamoriello said the team hopes he’ll begin skating in the near future. Duclair has been out with a lower-body injury since Oct. 19.

Mathew Barzal and Adam Pelech will begin skating as soon as they’ve been cleared by doctors, but no timeline has been established. Barzal has been out since Oct. 30 with an upper-body injury, while Pelech suffered an upper-body injury on Nov. 1.