In the United States, sudden cardiac arrest results in an estimated 300,000 deaths each year. However, many of those lives could be saved if bystanders performed cardiopulmonary resuscitation (CPR), suggest results from a study published by Duke researchers in the July 21 issue of the Journal of the American Medical Association.

CPR performed early by a person nearby, combined with defibrillation by firefighters or police before the arrival of emergency medical services (EMS), was the single intervention that substantially increased rates of survival from cardiac arrest, according to the study findings.

“We were surprised to learn that survival increased only for those who received bystander-initiated CPR compared with those who did not receive bystander-initiated CPR,” says lead author Carolina Malta Hansen, MD, of the Duke Clinical Research Institute. “Patients who received bystander or first-responder CPR and defibrillation were more likely to survive compared with those who received CPR and defibrillation once EMS arrived,” she explains.

Hansen says these results suggest that this early intervention is crucial and adds that CPR is something most bystanders can perform.

The researchers analyzed data from 4,961 cardiac arrest cases in 11 counties in North Carolina from 2010 to 2013. The data were gathered through a national registry that tracks cardiac arrests that occur outside of hospitals. The registry includes information about the responses of bystanders, first responders (firefighters, police officers, lifeguards, and other persons on the scene prior to the arrival of an ambulance), and EMS. It also tracks how well the persons experiencing cardiac arrest fared.

The 4-year time frame coincided with a campaign in North Carolina, called the HeartRescue Project, to encourage bystanders to perform chest-compression CPR—not mouth-to-mouth resuscitation—and to use an automated external defibrillator while awaiting an ambulance.

The HeartRescue Project also worked to improve the use of portable defibrillators, which are becoming increasingly available in public places and can be used by laypeople and first responders to shock a heart into typical rhythm.

Among the 11 counties included in the Duke trial, survival with good neurologic recovery improved by 37% during the study period. The researchers note that this substantial improvement in survival across a single state is a remarkable achievement.

The project included public training programs in defibrillators and compression-only CPR at schools, hospitals, and major events, as well as additional instruction for EMS and other emergency workers about optimal care for patients experiencing cardiac arrest.

During the study period, Hansen says that 86.3% of patients received CPR prior to EMS arrival (bystander CPR, 45.7%; first-responder CPR, 40.6%). Throughout the study period, a significant increase occurred in the proportion of patients receiving bystander-initiated CPR, from 39.3% in 2010 to 49.4% in 2013.

The proportion of patients who received bystander-initiated CPR and who also received defibrillation by first responders increased from 14.1% in 2010 to 23.1% in 2013. Bystander-initiated CPR, coupled with first-responder defibrillation, was associated with improved rates of survival compared with situations in which patients did not receive CPR and defibrillation until the arrival of EMS.

Of the 1,648 patients who were defibrillated, 53.9% were defibrillated prior to EMS (6.9% by bystanders and 47% by first responders). Use of first-responder defibrillation significantly increased from 40.9% in 2010 to 52.1% in 2013.

“During the past decade, there has been a focus on increasing bystander-initiated CPR,” explains senior author Christopher Granger, MD, cardiologist and director of the Cardiac Care Unit at Duke University. “Our findings show that survival can be improved by strengthening first-responder programs and encouraging more bystander CPR.”

He also adds that state and national programs that focus on community and EMS responses may help save more lives and improve the care of cardiac-arrest patients.