Ventricular Tachyarrhythmias after Cardiac Arrest in Public versus at Home

Abstract

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 by-stander, 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. (Funded by the National Heart, Lung, and Blood Institute and others.)

A Clinical Perspective on Sudden Cardiac Death

“…54,55 More recent studies, however, suggest that the incidence of VF or pulseless VT as the first recorded rhythm in out-of-hospital cardiac arrest has declined to <30 % in the past few decades. [56][57][58] Pulseless electrical activity (electromechanical dissociation) and asystole are proportionally more frequent mechanisms than VT/VF. Recent data demonstrate a pulseless electrical activity incidence of 19-23 %, with approximately 50 % of patients initially having asystole.…”

Does the number of rescuers affect the survival rate from out-of-hospital cardiac arrests? Two or more rescuers are not always better than one

“…This recommendation may be based on the assumption that an increased number of rescuers may facilitate the BLS actions. The majority of out-of-hospital cardiac arrests (OHCAs) occur at home, where the response to OHCAs and the characteristics of OHCA patients and their rescuers may differ from those in other locations [3,4,5,6]. The aging population accompanied with an increase in number of households with elderly residents [7][8][9] may influence not only the number of rescuers but also the performance of BLS [10,11,12].…”

Implantable Cardioverter-Defibrillators in Sudden Cardiac Death Prevention: What Guidelines Don't Tell

“…More recent studies suggest that the incidence of VF or VT as the first recorded rhythm in out-of-hospital cardiac arrest has declined to perhaps even <30% in the past several decades [17,23,26]. The risk of SCD in myocardial infarction (MI) survivors has also declined significantly over the past 30 years, presumably due to early reperfusion and optimal medical therapy practices [27].…”