The loss of the male sex chromosome as many men age causes the heart muscle to scar and can lead to deadly heart failure, new research shows. The finding may help explain why men die, on average, several years younger than women. Kenneth Walsh, Ph.D., says the new discovery suggests that men who suffer Y chromosome loss—estimated to include 40% of 70-year-olds—may particularly benefit from an existing drug that targets dangerous tissue scarring. The drug, he suspects, may help counteract the harmful effects of the chromosome loss—effects that may manifest not just in the heart but in other parts of...