mike reilly NYI heart procedure

Mike Reilly will undergo a heart procedure Tuesday and is out indefinitely, the New York Islanders announced Monday.

The 31-year-old defenseman is on injured reserve and has missed New York’s past seven games since sustaining a concussion after taking a hit from forward Jordan Greenway in the third period of a 4-3 win at the Buffalo Sabres on Nov. 1.

Reilly’s heart condition was previously undiagnosed and was discovered during concussion testing.

“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 Monday. "It's probably a blessing in disguise of what transpired. They detected this, something that you're sometimes born with but never knew."

There is no timetable for Reilly’s return.

"[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. It could be several months before he's back because of the type of procedure."

Reilly does not have a point in 11 games after signing a one-year contract July 1.

Defenseman Alexander Romanov, who has missed the past seven games and 10 of 11, is still day to day after sustaining an upper-body injury against the Sabres. He is a game-time decision when the Islanders (7-7-4) visit the Calgary Flames on Tuesday (9 p.m. ET; SN1, MSGSN).

Forwards Mathew Barzal (upper body) and Anthony Duclair (lower body), and defenseman Adam Pelech (upper body) have not resumed skating.