Last week, the nation’s leading heart organizations released new guidelines for lowering cholesterol, along with an online calculator meant to help doctors assess risks and treatment options. The calculator appears to greatly overestimate risk, so much so that it could mistakenly suggest that millions more people are candidates for statin drugs. Paul M. Ridker, the Eugene Braunwald Professor of Medicine, and Nancy Cook, HMS professor of medicine, both of Brigham and Women’s Hospital, identified the problems with the calculator.