Shockable cardiac arrests more common in public
January 26th, 2011
05:01 PM ET

Shockable cardiac arrests more common in public

Having a cardiac arrest that can be treated by electrical stimulation is more common in a public setting compared with having a cardiac arrest at home. That's the finding of a new study by Canadian and U.S. researchers, published in the New England Journal of Medicine.

When the heart’s electrical system malfunctions, causing it to beat irregularly, it’s called cardiac arrest. The irregular heartbeats are called arrhythmias. Two of the most common arrhythmias are ventricular fibrillation, when the lower heart chambers quiver rather than pumping blood properly to the body, and pulseless ventricular tachycardia, where the lower chambers beat rapidly, preventing the heart from filling with blood, and stopping the pulse. Death will result if the heart’s proper rhythm can’t be restored, and both arrhythmias can be treated by shocking the heart back into rhythm with an AED.

Researchers looked at data from 12,930 out-of-hospital cardiac arrests in ten locations in North America between 2005 and 2007. 2,042 occurred in public locations, including on streets or highways, public buildings, places of recreation or other public facilities, excluding health care facilities. 9,564 occurred in private locations, which included homes, nursing homes, or rural farmland locations.

“More than 300,000 Americans have an out-of-hospital arrest each year, with an estimated survival rate of 7.9% nationally, and the majority of survivors are in the subgroup of persons whose initial rhythm is ventricular fibrillation or pulseless ventricular tachycardia,” according to the study, which notes that clinical trials have shown that “using AEDs in public settings by trained laypersons improves survival” of the patient, while noting that studies of AED use in home settings haven’t shown the same benefits.

More than twice as many cardiac arrest patients had shockable heart rhythms in public settings versus home settings and their post-hospital survival rates were much higher. The study found that 36% of home cardiac arrest patients had ventricular fibrillation or pulseless ventricular tachycardia when a bystander applied an AED, 35% when it was witnessed by a bystander, and 25% when witnessed by emergency medical service responders. In public settings 79% had ventricular fibrillation or pulseless ventricular tachycardia when a bystander applied an AED, 60% when it was witnessed by a bystander, and 38% when witnessed by an EMS responder. Rates of survival after leaving the hospital were also higher for public incidents with 34% for public settings, versus 12% survival for arrests at home.

The study explains the lower home rates of shockable heart rhythms noting that people who have cardiac arrest at home are often older, living with one or more chronic health conditions, and have limited ability to participate in public activities.

The researchers conclude that their study “adds strength to the argument for putting AEDs in public locations,” while their findings about home cardiac arrests “suggests that a treatment strategy that emphasizes prompt, bystander-delivered CPR of high quality (e.g., with the assistance of a dispatcher) should be as effective in saving lives as the widespread deployment of AEDs in homes.”

soundoff (7 Responses)
  1. E.Ham

    Would a Taser suffice? If so, many might be saved because of the cop on the beat.

    January 27, 2011 at 11:17 | Report abuse | Reply
  2. E.Ham

    To amplify, if a Taser might work then providing a "Cardiac Arrest" (no pun intended) setting on the weapon would be in order.

    January 27, 2011 at 11:19 | Report abuse | Reply
  3. E. Swenson

    One cannot read this without looking at the editorial, A Critic's Assessment of Our Approach to Cardiac Arrest, in the same issue of the New England Journal. Very enlightening, and discounts the findings of Weisfeldt et al.

    January 27, 2011 at 11:36 | Report abuse | Reply
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