Danny Ainge suffered a mild heart attack in Milwaukee on Tuesday evening.
Ainge received immediate medical attention and is expected to make a full recovery and will return to Boston shortly.
"Been in constant communication with his family," Celtics coach Brad Stevens said Thursday. "He's resting well and feels better. Obviously, always scary, but he's got a good support network. Obviously, expect a full recovery and he's feeling good. So that's all positive. Certainly scary."
Ainge also suffered a minor heart attack in 2009.