The chance of surviving an out-of-hospital cardiac arrest at work or in the home has not improved since the 1950s, according to a report published online Nov. 10 in Circulation: Cardiovascular Quality and Outcomes.

The analysis showed only 7.6 percent of victims survive an out-of-hospital cardiac arrest--a number that has not changed significantly in almost 30 years.

It’s a dismal trend considering enormous spending on heart research, new emergency care protocols, and the advent of new drugs and devices such as defibrillators, according to researchers from the University of Michigan (U-M) Health System in Ann Arbor, Emory University in Atlanta and the University of Rochester in N.Y.

The researchers reported that there are key factors that can make a difference in saving lives when cardiac arrest happens at home, a hotel, restaurant or workplace.

“Our study shows that patients with a heart rhythm that can be shocked, or who have bystander CPR or a pulse restored at the scene of the event are associated with a much larger chance of survival,” said lead author Comilla Sasson, MD, a Robert Wood Johnson Scholar and emergency medicine physician at the U-M Health System.

Although half of cardiac arrests are witnessed by a bystander, according to the study, only 32 percent are receiving bystander CPR.

According to the authors, this is the first study to look at the associations between five clinical variables and overall survival from an out-of-hospital cardiac arrest.

The variables studied included: witnessed by emergency medical services provider, bystander CPR, types of heart rhythm–asystole vs. ventricular fibrillation and return of spontaneous circulation.

Researchers evaluated data on 142,740 patients from 79 studies published internationally between January 1950 and August 2008.

Here’s what they found:

• Of the more than 140,000 patients, only 23.8 percent survived to hospital admission, and 7.6 percent lived to be discharged from the hospital.

• Cardiac arrest victims who received CPR from a bystander or an emergency medical services provider and those who had a shockable heart rhythm were more likely to survive.

• The strongest predictor of survival was a return of spontaneous circulation at the scene. Among them, 15.5 percent (in low-performing EMS systems) to 33.6 percent (in high performing EMS systems) survived.

“Increasing bystander CPR rates, increasing the awareness and use of devices to shock the heart, and keeping paramedics on scene until they restore a person’s pulse needs to occur if we are ever going to change our dismal survival rate,” Sasson said.

Geographic areas, like Seattle, which have the highest rates of cardiac arrest survival in the U.S., are doing these three basic things exceptionally well, she said.

The lack of progress in survival across the U.S. and abroad may be linked to an aging population, a lower number of people who are found in a shockable rhythm (which is associated with the highest chance of survival) and longer EMS drives due to the increasing size of cities and traffic congestion, the authors write.

While the overall rate of out-of-hospital cardiac arrest survival has not improved, the field of cardiac and cerebral resuscitation is rapidly evolving.

Most of the studies in the analysis were conducted before the advent of therapeutic hypothermia, which has been shown to benefit resuscitated patients.

Also, studies did not distinguish between patients treated with traditional CPR and those cared for under new AHA guidelines for CPR which emphasize chest compressions over mouth-to-mouth resuscitation.