Home AEDs Don't Help

April 1, 2008

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<http://content.nejm.org/cgi/content/short/NEJMe0801992v1> Editorial

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ABSTRACT

Background The most common location of out-of-hospital sudden cardiac arrest

is the home, a situation in which emergency medical services are challenged

to provide timely care. Consequently, home use of an automated external

defibrillator (AED) might offer an opportunity to improve survival for

patients at risk.

Methods We randomly assigned 7001 patients with previous anterior-wall

myocardial infarction who were not candidates for an implantable

cardioverter-defibrillator to receive one of two responses to sudden cardiac

arrest occurring at home: either the control response (calling emergency

medical services and performing cardiopulmonary resuscitation [CPR]) or the

use of an AED, followed by calling emergency medical services and performing

CPR. The primary outcome was death from any cause.

Results The median age of the patients was 62 years; 17% were women. The

median follow-up was 37.3 months. Overall, 450 patients died: 228 of 3506

patients (6.5%) in the control group and 222 of 3495 patients (6.4%) in the

AED group (hazard ratio, 0.97; 95% confidence interval, 0.81 to 1.17;

P=0.77). Mortality did not differ significantly in major prespecified

subgroups. Only 160 deaths (35.6%) were considered to be from sudden cardiac

arrest from tachyarrhythmia. Of these deaths, 117 occurred at home; 58

at-home events were witnessed. AEDs were used in 32 patients. Of these

patients, 14 received an appropriate shock, and 4 survived to hospital

discharge. There were no documented inappropriate shocks.

Conclusions For survivors of anterior-wall myocardial infarction who were

not candidates for implantation of a cardioverter-defibrillator, access to a

home AED did not significantly improve overall survival, as compared with

reliance on conventional resuscitation methods. (ClinicalTrials.gov number,

NCT00047411 [ClinicalTrials.gov]

<http://content.nejm.org/cgi/external_ref?access_num=NCT00047411 & link_type=C

LINTRIALGOV> .)

Just when we thought we knew....

E. Bledsoe, DO, FACEP

Midlothian, Texas

Mark Your Calendars!

EMStock 2008

September 25-28, 2008

http://www.emstock.com

April 1, 2008

Then this comes out from the NIH:

U.S. Department of Health and Human Services

NATIONAL INSTITUTES OF HEALTH NIH News

National Heart, Lung, and Blood Institute (NHLBI) <http://www.nhlbi.nih.gov/>

Embargoed For Release: Tuesday, April 1, 2008, 9:30 a.m. EDT

Contacts: NHLBI Communications Office, , <e-mail:

NHLBI_news@...>

AUTOMATED EXTERNAL DEFIBRILLATORS AND CPR ARE EQUALLY HELPFUL FOR SUDDEN CARDIAC

ARREST IN THE HOME

Study Finds AEDs Underused at Home

The first study to explore the use of automated external defibrillator (AEDs) in

the home has found that although the safe and easy-to-use devices are effective

for certain types of cardiac arrest, they were underused. The Home Automated

External Defibrillator Trial (HAT), a randomized international clinical trial,

was supported by the National Heart, Lung, and Blood Institute (NHLBI) of the

National Institutes of Health.

Researchers will present their findings from the international study at the 2008

American College of Cardiology (ACC) Scientific Sessions in Chicago April 1. The

results are being published online simultaneously by the " New England Journal of

Medicine " and will appear in the April 24 print edition. An editorial by

Callans, M.D., of the University of Pennsylvania accompanies the article

Researchers followed 7,001 heart attack patients at moderate risk of sudden

cardiac arrest who had a spouse or other live-in companion who agreed to take

conventional steps to respond to a sudden cardiac arrest -- calling emergency

medical services (EMS) and performing cardiopulmonary resuscitation (CPR) --

with households that were asked to use an AED before taking conventional

life-saving steps. After an average of just over three years of follow-up,

researchers found that survival rates were about the same between those who had

an AED in the home and those who did not. However, there were relatively few

sudden cardiac arrests, and only 39 percent of these events were witnessed at

home. The study was conducted in 178 clinical sites in the United States,

Canada, Britain, New Zealand, Australia, Germany, and the Netherlands.

" Cardiac arrest is a top killer of Americans, and this study shows that the

strategies of placing an AED in the home and of being prepared to give CPR are

equally effective at saving lives in a population at risk for sudden cardiac

arrest, " noted G. Nabel, M.D., NHLBI director. " The important message

here is that every minute counts, and quick action is key. Use an AED if one is

handy or perform CPR -- and always call for help by emergency medical

professionals, such as by dialing 911. "

Every two to three minutes, someone in the United States goes into cardiac

arrest, and at least 95 percent of cases end in death within a few minutes.

Three out of four sudden cardiac arrests take place when the patient is at home.

During sudden cardiac arrest, the heart suddenly and unexpectedly stops beating

effectively; blood stops flowing to the brain and other vital organs, and the

individual collapses into unconsciousness and stops breathing. Although sudden

cardiac arrest is not the same as a heart attack, which is the result of a loss

of blood supply to the heart muscle, a heart attack increases the risk for

sudden cardiac arrest.

The most common cause of sudden cardiac arrest is ventricular fibrillation, in

which a problem in the heart's internal electrical system causes the large

pumping sections of the lower part of the heart (the ventricles) to disrupt the

normal rhythm. In these cases, an electric shock from an AED within a few

minutes of onset can significantly improve a patient's chance of survival by

restoring the heart to its normal rhythm. CPR has also been shown to be

effective in increasing survival from sudden cardiac arrest.

" The long-term survival rates of all of the HAT participants who went into

cardiac arrest were significantly higher than what is typically found in the

general population, and fewer of the participants than expected had sudden

cardiac arrest, " noted Gust H. Bardy, M.D., of the Seattle Institute for Cardiac

Research, lead author of the study. " We believe that this is because of the

optimal medical therapy and coronary revascularization that all HAT participants

received following heart attack. Moreover, although the control arm mortality

rates in HAT were equal to the AED group, it is not routine practice to train

spouses or other companions following a patient's heart attack on why and how to

call emergency medical services for help and how to perform CPR. I believe this

should be routine practice following a patient's heart attack, regardless of

whether they have an AED in the home. "

AEDs detect the patient's heart rhythm through electrodes that are applied to a

patient's chest. If the AED determines that the problem is caused by ventricular

fibrillation, the AED instructs the user to hit a button to deliver an electric

shock. The AED transmits the shock through the electrodes, then rereads the

heart rhythm to determine if another shock is needed. The machine does not

recommend or administer a shock if the cause of the abnormal rhythm cannot be

treated by the shock. HAT researchers found no evidence of inappropriate uses of

the AED by lay users.

All HAT participants previously had a heart attack and were at moderately

increased risk for sudden cardiac arrest. Participants also had to have a family

member or other live-in companion who was willing to follow specific steps to

immediately help the participant in cardiac arrest; these steps were described

in a training video and through discussions with study personnel. One-half of

the companions (control group) was asked to call EMS and perform CPR

immediately; the other half of the group was asked to use an AED before calling

EMS (or at the same time, if there were two bystanders) and performing CPR.

Participants were followed for about 3 years (ranging from 20 months to 56

months).

Overall, 450 participants died during the study, with nearly equal numbers of

participants in the control group (228 or 6.5 percent) and the AED treatment

group (222 or 6.4 percent). Participants were equally likely to die from sudden

cardiac arrest (35.6 percent) as from other causes not related to cardiovascular

disease (37.8 percent), and 160 deaths during the study were due to sudden

cardiac arrest.

Of the 117 sudden cardiac arrests that occurred at home, only one-half (58) of

them were witnessed by another member of the household.

" We knew that the vast majority of sudden cardiac arrests would happen at home,

but we didn't expect that so few would be witnessed by a spouse or other member

of the household, " explained Bardy. " This of course dramatically limits the

chance that someone would be there to use an AED or to perform CPR. However,

when the AEDs were used, they were safe and effective. "

AEDs were used by at-home bystanders on 32 HAT participants, with ventricular

fibrillation detected in 15 participants. Fourteen of these participants were

shocked, and ventricular fibrillation was terminated in each case. There were no

device failures. Overall, among the participants in the AED group who used the

AED for ventricular fibrillation in the home, four of the 14 participants

defibrillated (28.6 percent) survived long term -- an improvement over the

estimated 2 to 6 percent long-term survival rates typically reported. In

addition, AEDs were used on seven neighbors or visiting friends, and shock was

advised and successfully given in four individuals, of whom two survived

long-term.

The AEDs used in the study are the same types of devices that are now available

in many airports, fitness centers, and other public places, which have been

shown to be safely and easily used by bystanders with little training to perform

life-saving treatment on individuals in cardiac arrest.

" Studies of public access to AEDs have shown that AEDs can be highly effective

in helping people survive sudden cardiac arrest, " said Eleanor B. Schron, PhD,

NHLBI project officer of the study and a coauthor of the paper. For example, in

the NHLBI-supported Public Access Defibrillation Trial, nearly twice as many

people survived sudden cardiac arrest in communities where volunteers were

trained to use AEDs as well as CPR compared to communities where community

volunteers learned CPR only.

Rick LaChance, BA, LEMTP

Emergency Medicine Education

UT Southwestern Medical Center

Dallas, TX 75390-8890

On 4/1/2008 at 11:35 AM, in message <007301c89416$69eab540$3dc01fc0$@net>,

" Bledsoe, DO " wrote: