Perishock Pause: An Independent Predictor of Survival From Out-of-Hospital Shockable Cardiac Arrest

Study Questions:

What is the prognostic significance of perishock pauses in chest compressions during cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest?


Registry data collected during CPR in 815 patients (mean age 64 years) with cardiac arrest from ventricular tachycardia/ventricular fibrillation (VT/VF) were analyzed. Preshock pause was defined as the interval from chest compression cessation to shock delivery, and postshock pause was defined as the interval between shock delivery and resumption of chest compressions. The perishock pause was the total of the preshock and postshock pauses. The primary endpoint was survival to hospital discharge (SHD).


The median preshock and postshock pauses were 15.6 and 8.3 seconds, respectively. Compared to a preshock pause <10 seconds, a preshock pause ≥20 seconds was associated with a 53% lower odds of SHD. Postshock pauses were not independently associated with SHD. The odds of SHD were 18% lower for every 5-second increase in preshock pause.


The authors concluded that in patients undergoing resuscitation for cardiac arrest caused by VT/VF, longer preshock pauses in chest compressions are an independent predictor of mortality.


The results emphasize the critical importance of chest compressions during CPR. The preshock delay is largely dictated by the time required for an automatic defibrillator to analyze the underlying rhythm, the charge time, and the time to deliver the shock or to prompt the user to deliver the shock. The preshock delay could be considerably shortened by the development of defibrillator software that allows rhythm analysis during ongoing chest compressions.

Clinical Topics: Arrhythmias and Clinical EP, Implantable Devices, SCD/Ventricular Arrhythmias

Keywords: Defibrillators, Tachycardia, Ventricular, Out-of-Hospital Cardiac Arrest, Cardiopulmonary Resuscitation, Ventricular Fibrillation, Heart Arrest

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