Mortality rates among Americans who arrive at a hospital in cardiac arrest decreased steadily, from 69.6% to 57.8%, from 2001 to 2009. National hospital discharge data on 1,190,860 heart attack patients were examined. The report, published in the July 31 issue of Circulation, couldn't pinpoint specific reasons for the improvement. However, the authors suspect it's a combination of improved hospital treatments, such as hospitals treating patients with therapeutic hypothermia, and increased public awareness regarding what to do when someone has a heart attack-bystanders may be more willing to perform hands-only resuscitation (which doesn't involve mouth-to-mouth resuscitation). The authors emphasize that the decrease in mortality applies only to cardiac arrest patients who make it to a hospital.