The Chain of Survival from Sudden Cardiac Arrest

Research shows that the earlier an SCA victim is helped, the greater the chance of survival. Schools can play a critical role by taking the first steps in the well-known “chain of survival”

Sudden cardiac arrest (SCA) is a sudden and unexpected pulseless condition caused by a disturbance in the heart’s electrical activity. The electrical disturbance may be due to a heart attack, a severe imbalance of electrolytes, an inherited genetic mutation that predisposes the heart to electric abnormalities, an electric shock (e.g., from lightning), or blunt force trauma to the chest leading to commotio cordis. Symptoms include an almost instantaneous loss of consciousness and collapse. The treatment goal for SCA is to restore a healthy heart rhythm and good neurological outcome. (Graham R, 2015)

SCA strikes approximately 326,200 (Mozaffarian D, 2015) to 395,000 (Graham R, 2015) individuals outside hospitals each year in the U.S., including an estimated 6,328 people less than 18 years of age (Mozaffarian D, 2015). On average, about one in 10 victims survives (Graham R: 6%; Mozaffarian D: 10.6%), though some high performing communities have achieved survival rates of more than 60% for specific types of cardiac arrest (Graham R, 2015).

The majority of people who survive SCA invariably receive immediate help from bystanders at the scene. The time between the onset of arrest and the provision of care determines the likelihood of survival. If treatment is not provided within 10 minutes, the survival rate is close to zero. Because minutes count, the public plays a crucial role in saving lives threatened by SCA. (Graham R, 2015)

The “Chain of Survival” refers to the chain of events that must occur in rapid succession to maximize the chances of survival from SCA. When the Chain of Survival metaphor was first created and described, it included early recognition, early access, early CPR, early defibrillation and early advanced life support (Newman M, 1989, 1990). The metaphor was a simple way to educate the public about its vital role in helping SCA victims, suggesting that each link is critical and interdependent, and the Chain of Survival is only as strong as its weakest link.

The concept was later adopted by the American Heart Association (Cummins R, 1991) and other health organizations. Subsequently, the Chain of Survival was revisited to emphasize the importance of early recognition and response (Newman M, Bahr R, 1998).

As post-resuscitation care options expanded to include mild therapeutic hypothermia and other treatments, another link, integrated post-cardiac arrest care, was added to the Chain (Hazinski M, 2010).

Today, the links in the American Heart Association version of the Chain of Survival are:

  1. Immediate recognition of cardiac arrest and activation of the emergency response system
  2. Early CPR with an emphasis on chest compressions
  3. Rapid defibrillation
  4. Effective advanced life support
  5. Integrated post-cardiac arrest care.

Bystanders can help save lives by addressing the first three links in the Chain of Survival. Action steps for bystanders are described below.


1. Immediate recognition of cardiac arrest and activation of the emergency response system

Action steps

  • Recognize the emergency and decide to act.  
  • Call 9-1-1 or the local emergency number, activate the on-site emergency response system (e.g., by phone or text), and send someone to retrieve the nearest automated external defibrillator (AED). If the rescuer is alone, he or she should retrieve the AED immediately.


  • A medical emergency can be ambiguous, confusing and frightening, which can delay effective action (Braslow A). Nevertheless, it is critical to make the decision to help and take action immediately.
  • If the victim is unresponsive, not breathing or not breathing normally, he or she could be in cardiac arrest. The SCA victim may experience several seconds of seizure activity and agonal breathing, or gasping. The rescuer should suspect cardiac arrest if the victim is not breathing normally or only gasping.

2. Early CPR with an emphasis on chest compressions

Action steps

  • Start CPR immediately.


  • Decreasing the time between cardiac arrest onset and the first chest compression is critical to survival (Graham, 2015).
  • If the bystander is not trained in CPR, he or she should provide hands-only or compression-only CPR by pushing hard and fast on the center of the chest at a rate of at least 100 compressions per minute.
  • For adult victims, the compression depth should be at least two inches. For young victims (age 1-8) the compression depth should be about two inches, or about one-third the diameter of the chest.
  • The rescuer should allow the chest to recoil completely between compressions.
  • The rescuer should continue CPR until an AED is ready for use or EMS providers take over care of the victim.
  •  In the event the bystander is trained and proficient in CPR, he or she should provide 30 compressions followed by two breaths and repeat this cycle until an AED is ready for use or EMS providers take over care of the victim.
  • Emergency dispatchers in many EMS systems will coach bystanders in their efforts to save lives. They will guide rescuers through compression-only CPR, and in the event of an asphyxial arrest such as drowning, dispatchers will also provide guidance on rescue breathing.

3. Rapid defibrillation

Action steps

  • As soon as an AED is available, the rescuer should position the device next to the patient, turn it on, and follow visual and voice prompts. He or she should then attach the electrode pads to the victim’s bare chest as shown in the diagram on the pads. If a shock is advised, the rescuer should be sure no one is touching the victim and then press the shock button.


  • If a shock is needed, the device will instruct the rescuer to press the shock button. In fully automatic devices, the shock will be delivered automatically.
  • AEDs are designed for use by untrained laypersons. They are safe, effective, and intuitive devices that will not shock a victim unless a shock is needed to restore a normal heartbeat. They cannot harm the victim.
  • AEDs are safe for use with children. If the child is age 1-8 and a pediatric dose-attenuator is available, the rescuer should use it. If this adapter is not available, the rescuer should use a standard AED.


The two remaining links in the Chain of Survival refer to actions that should be taken by professional responders. They include advanced life support and integrated post-cardiac arrest care.

4. Effective advanced life support

Advanced life support refers to high-quality CPR, early defibrillation, and use of devices and drugs.

5. Integrated post-cardiac arrest care

Integrated post-cardiac arrest care refers to a comprehensive, multidisciplinary system of care including mild therapeutic hypothermia and other treatments.


Cardiac arrest treatment is a community issue requiring a wide range of people to be prepared to act—including bystanders, family members, first responders, emergency medical personnel, and other healthcare providers. Bystander CPR and AED use can significantly improve outcomes from cardiac arrest (Graham, 2015).

-Mary M. Newman, MS


Braslow A., Principal Investigator, U. S. Department of Transportation & Metropolitan Dade County Office of Trauma Services (1992). National Standard Curriculum for Bystander Care, Washington, DC: US
Cummins RO, Ornato JP, Thies WH, et al. Improving survival from sudden cardiac arrest: the “chain of survival” concept: A statement for health professionals from the Advanced Cardiac Life Support Subcommittee and Emergency Cardiac Care Committee, American Heart Association. Circulation 1991;83:1832-1847.
Graham R, Eisenberg M, et al. Strategies to improve survival: A time to act. Institute of Medicine Report, pre-publication copy.  See SCA Foundation summary here:
Hazinski, M, editor. 2010 AHA Guidelines for CPR and ECC
Mozaffarian D, et al. Heart Disease and Stroke Statistics—2015 Update. Circulation. 2015;131:00-00. See SCA Foundation summary here:
Newman, MM, The chain of survival takes hold. Journal of Emergency Medical Services 1989;14:11-13.
Newman, MM, The chain of survival: converting a nation (editorial). Currents in Emergency Cardiac Care 1990;1(1):3.
Newman, MM. The chain of survival revisited: The emergence of early recognition as the unsung vital link. Journal of Emergency Medical Services 1998;23(5).