No. The men in LBJ’s family had a history of dying relatively young and of heart trouble. LBJ was nearly killed by a massive heart attack in 1955 when he was Senate Majority Leader. He worked exceedingly hard, took no type of exercise whatsoever, had few interests outside of politics and governing, and when he left the White House, he went home to Texas and started chain-smoking cigarettes once again. I don’t think anyone was surprised that he died at 64, including LBJ himself.