Individuals previously diagnosed with heart disease may be less likely to experience heart failure, heart attacks, or stroke, or to die from these events, if they have higher blood levels of two very closely related proteins, according to a new study led by a UC San Francisco research team.One of these proteins, known as GDF11, has attracted great interest since 2013, when researchers showed that it could rejuvenate old mice. Based on these findings, scientists have speculated that drugs that increase GDF11 levels might reverse physiological manifestations of aging that lead to heart failure in people.