Cardiovascular disease has long been the world's leading life-threatening cause, often striking patients suddenly and without warning, but in a huge new analysis of more than 9 million adults, almost every heart attack and stroke is preceded by one of four specific, largely controllable risk factors. The research, published in the Journal of the American College of Cardiology, reveals a startling statistic: When combined, these four factors together accounted for 99% of all cases of major cardiovascular disease in the populations studied.