Ventricular tachyarrhythmias after cardiac arrest in public versus at home.
BACKGROUND
The incidence of ventricular fibrillation or pulseless ventricular tachycardia as the first recorded rhythm after out-of-hospital cardiac arrest has unexpectedly declined. The success of bystander-deployed automated external defibrillators (AEDs) in public settings suggests that this may be the more common initial rhythm when out-of-hospital cardiac arrest occurs in public. We conducted a study to determine whether the location of the arrest, the type of arrhythmia, and the probability of survival are associated.


METHODS
Between 2005 and 2007, we conducted a prospective cohort study of out-of-hospital cardiac arrest in adults in 10 North American communities. We assessed the frequencies of ventricular fibrillation or pulseless ventricular tachycardia and of survival to hospital discharge for arrests at home as compared with arrests in public.


RESULTS
Of 12,930 evaluated out-of-hospital cardiac arrests, 2042 occurred in public and 9564 at home. For cardiac arrests at home, the incidence of ventricular fibrillation or pulseless ventricular tachycardia was 25% when the arrest was witnessed by emergency-medical-services (EMS) personnel, 35% when it was witnessed by a bystander, and 36% when a bystander applied an AED. For cardiac arrests in public, the corresponding rates were 38%, 60%, and 79%. The adjusted odds ratio for initial ventricular fibrillation or pulseless ventricular tachycardia in public versus at home was 2.28 (95% confidence interval [CI], 1.96 to 2.66; P < 0.001) for bystander-witnessed arrests and 4.48 (95% CI, 2.23 to 8.97; P<0.001) for arrests in which bystanders applied AEDs. The rate of survival to hospital discharge was 34% for arrests in public settings with AEDs applied by bystanders versus 12% for arrests at home (adjusted odds ratio, 2.49; 95% CI, 1.03 to 5.99; P = 0.04).


CONCLUSIONS
Regardless of whether out-of-hospital cardiac arrests are witnessed by EMS personnel or bystanders and whether AEDs are applied by bystanders, the proportion of arrests with initial ventricular fibrillation or pulseless ventricular tachycardia is much greater in public settings than at home. The incremental value of resuscitation strategies, such as the ready availability of an AED, may be related to the place where the arrest occurs.
Johns Hopkins University, Baltimore, MD 21287, USA. mlw5@jhmi.edu
Myron L
ML
Weisfeldt
Siobhan
S
Everson-Stewart
Colleen
C
Sitlani
Thomas
T
Rea
Tom P
TP
Aufderheide
Dianne L
DL
Atkins
Blair
B
Bigham
Steven C
SC
Brooks
Christopher
C
Foerster
Randal
R
Gray
Joseph P
JP
Ornato
Judy
J
Powell
Peter J
PJ
Kudenchuk
Laurie J
LJ
Morrison
D000367:Age Factors; D000368:Aged; D016887:Cardiopulmonary Resuscitation; D015897:Comorbidity; D047548:Defibrillators; D004638:Emergency Treatment; D005260:Female; D006323:Heart Arrest / Q000150:complications* / Q000401:mortality / Q000628:therapy; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015996:Survival Rate; D017180:Tachycardia, Ventricular / Q000453:epidemiology / Q000209:etiology*; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000453:epidemiology / Q000209:etiology*; D014838:Volunteers
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