Smith Hart, brother of WWE Hall of Famer Bret Hart, posted on Twitter earlier that he was told Jerry Lawler was "clinically dead" before being revived.

"According to my friend Jeremy Prophet who was backstage at RAW, Jerry was clinically dead for 20 min before being brought back by defibrilat"

It has been confirmed by multiple sources that Lawler did indeed suffer a heart attack.  He is currently in the hospital and recovering.

Source: http://es.twitter.com/SmithHart1