Watch: Demi Lovato DEFENDS Singing “Heart Attack” at Cardiovascular Disease Event. Demi Lovato is sporting a bright new ‘do. The “Heart Attack” singer has debuted a chic honey brown-dyed, flipped bob, days after she sported a longer, lob hairstyle in her signature dark brunette color at the Baby2Baby Mother’s Day celebration, presented by Aquaphor Baby, at The Grove shopping Center in Los Angeles.