"I have an arrhythmia issue I'm trying to get corrected," Paxson said in a statement released by the Bulls on Sunday. "It is something I've had before and planned this procedure over one month ago. Nothing more to it than that and had not intended for it to be made public."
The news became public after Philadelphia 76ers coach Doug Collins mentioned it in a postgame news conference following his team's 89-82 Game 4 victory Sunday in Philadelphia.
"I want to send my prayers out to John Paxson," Collins said. "(He) had a little bit of a heart surgery, he's not going to be able to be at Games 4 and 5. He's like a son to me. They've been hit with a lot of stuff, but Pax is so much the guts of that organization, I want to send out prayers to him. I hope you guys will too."
Collins, an Illinois native, coached the Bulls for three seasons from 1986-89, during which Paxson was a player under him.
Collins' Sixers have the chance to eliminate the Bulls in Tuesday night's Game 5 in Chicago.