Randy Jackson -- Not His First Heart Attack

Randy JacksonTMZ has learned Randy Jackson -- MJ's brother -- was extra cautious about handling his chest pains yesterday because he's experienced a heart attack in the past.

As we previously reported, Randy checked himself into a Pasadena hospital yesterday -- but a rep from the family tells us Randy is now back at home and "doing OK."

It's unclear when Randy suffered his previous heart attack -- or how severe it was.