The Hard Facts about Sudden Cardiac Arrest

Jun 8th, 2011 | By | Category: Response Times
 

Sudden cardiac arrest (SCA) is one of the leading causes of death among adults in North America. Each year, it claims the lives of an estimated 225,000 in the United States alone. Once every one or two minutes, another American succumbs suddenly, without warning.

Most victims of sudden cardiac arrest are middle-aged or elderly. Though the average victim is about 65-years-old, some victims are in their 30s or 40s. Most collapse at home. For many, there is no previous history of heart problems. Sudden cardiac arrest is often the first symptom.

Although victims of sudden cardiac arrest tend to fit in certain categories, sudden cardiac arrest, by its nature, is completely unpredictable. It can strike anyone, anywhere, any time. Chances are you know someone who has experienced sudden cardiac arrest-a friend, a relative or a co-worker.

Sudden cardiac arrest does not have to be fatal

Sudden cardiac arrest does not have to result in “sudden death.” When sudden cardiac arrest occurs, most victims have an abnormal heart rhythm called ventricular fibrillation (VF). When the heart is in this state, it cannot beat in a coordinated fashion and blood does not circulate to the heart and the brain. First, the pulse stops. Then, breathing stops. The victim loses consciousness, collapses and appears lifeless.

But the victim doesn’t have to stay that way. Ventricular fibrillation is a treatable rhythm. In this state, electrical energy is present in the heart, but it is chaotic. If the heart can be shocked quickly with a defibrillator, a normal heart rhythm may be restored. This is called defibrillation. If this shock is delivered within minutes after collapse, many victims can survive.

The key is to be quick

Studies conducted at cardiac rehabilitation centers have shown that when sudden cardiac arrest victims in ventricular fibrillation receive defibrillation therapy within the first minute or two after collapse, more than 90 percent survive to be discharged from the hospital.

In more typical community settings, victims of sudden cardiac arrest rarely survive. Why? Most victims do not have immediate access to prompt, definitive treatment. Too much time elapses before the defibrillator arrives-if it arrives at all.

In New York City, for example, the average emergency response time is relatively long-about 12 minutes-due in part to traffic delays and the logistics of getting to victims in high-rise buildings. There, only 5 percent of witnessed VF victims-1 to 2 percent of all cardiac arrest victims-survive.

Seattle, on the other hand, has achieved an average response time of seven minutes and a VF survival rate of 30 percent. In Rochester, Minnesota, response times average six minutes and 45 percent of VF victims survive.

In all reports of survival, the shorter the time from collapse to defibrillation, the better the chances of survival. If defibrillation is delayed for more than 10 minutes, survival rates drop to less than 5 percent.

Every minute counts
Time from notification to defibrillation Survival
rate*
Rehabilitation centers Immediate defibrillation (1-2 minutes) 90%
Model community Early defibrillation (6 minutes) 45%
Early defibrillation (7 minutes) 30%
Typical community Delayed defibrillation (>10 minutes) <5%
* For victims of sudden cardiac arrest in witnessed ventricular fibrillation

It is impossible in most community settings to respond consistently to sudden cardiac arrest victims within the one to two minute timeframe documented in some cardiac rehabilitation centers. But all communities can aim to reduce the critical interval from collapse to defibrillation. Since the exact time of collapse often is difficult to identify and measure, communities can focus on minimizing the interval from the 911 call to the first defibrillatory shock. Communities that reduce this “call-to-shock” time to five minutes or less can expect as many as one-third to one-half of sudden cardiac arrest victims found in ventricular fibrillation to be resuscitated. Reducing “call-to-shock” time by even one minute can mean the difference between life and death.

Survival timeline:
Communities should aim to reduce “call-to-shock” time interval

Survival Timeline

Once victims are resuscitated, the prospects for long term recovery are very promising. Eight in 10 survivors will live at least a year longer. Six in 10 survivors will live five more years.

The American Heart Association and other organizations have adopted a simple action plan designed to help communities improve survival from sudden cardiac arrest in adults. This plan is called the Chain of Survival.

Summary

Sudden cardiac arrest kills one adult every one to two minutes. The key to survival is prompt defibrillation. The challenge for communities is to respond, defibrillator in hand, to every victim of sudden cardiac arrest within minutes. If the time from 911 call to defibrillation is seven minutes or less, as many as one-third to one-half of sudden cardiac arrest victims found in ventricular fibrillation can be resuscitated.

Article courtesy of National Center for Early Defibrillation.

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