More than 99% of people who suffer a heart attack, stroke, or heart failure have at least one risk factor beforehand—yet many have no idea until it’s too late. That’s part of the reason why heart disease has been the leading cause of death in the U.S. since at least 1950 . Now, scientists hope that a new generation of tools—like a first-of-its-kind risk calculator—can turn those invisible warning signs into something people can see, understand, and act on years before the worst-case scenario