Double Sequential External Defibrillation for Refractory Ventricular Fibrillation - DOSE VF

Contribution To Literature:

The DOSE VF trial showed that double sequential external defibrillation and vector-change defibrillation led to greater survival to hospital discharge for patients with refractory ventricular fibrillation and out-of-hospital cardiac arrest.


The goal of the trial was to evaluate the safety and efficacy of double sequential external defibrillation (DSED; rapid sequential shocks from two defibrillators) and vector-change (VC) defibrillation (switching defibrillation pads to an anterior-posterior position) compared to standard defibrillation among patients who remain in refractory ventricular fibrillation (VF) during out-of-hospital cardiac arrest.

Study Design

This was a cluster-randomized controlled trial with crossover in six paramedic services in Ontario, Canada. All patients received initial defibrillation according to standard protocol for three defibrillation attempts with pad position anterior-lateral. Eligible patients who remained in VF after three consecutive shocks had been delivered received one of three types of defibrillation according to the random assignment for the cluster: standard defibrillation (n = 136) with pads in the original anterior-lateral position; VC defibrillation, with pads in the anterior-posterior configuration (n = 144); or DSED, with a second set of defibrillation pads (provided by a second defibrillator) in the anterior-posterior position (n = 125) with a short delay (<1 second) between shocks. The trial was stopped early by the data and safety monitoring board.

  • Total screened: 450
  • Total randomized: 405
  • Mean patient age: 64 years
  • Percentage female: 15.6%

Inclusion criteria:

  • Refractory VF, defined as VF or pulseless VF present after three consecutive rhythm analyses and standard defibrillations

Other salient features/characteristics:

  • 67.9% out-of-hospital cardiac arrests witnessed by bystanders
  • 58.0% received bystander CPR

Principal Findings:

The primary outcome, survival to hospital discharge, for standard vs. VC vs. DSED defibrillation, was: 13.3% vs. 21.7% vs. 30.4% (p = 0.009).

Secondary outcomes for standard vs. VC vs. DSED defibrillation:

  • Termination of ventricular fibrillation: 67.6% vs. 79.9% vs. 84.0%
  • Return of spontaneous circulation: 26.5% vs. 35.4% vs. 46.4%
  • Modified Rankin scale score ≤2: 11.2% vs. 16.2% vs. 27.4%


The results of this trial indicate that survival to hospital discharge was greater among patients who received DSED or VC defibrillation versus standard defibrillation for refractory VF. This trial highlights two important treatment options for patients with refractory VF, and both were better than standard defibrillation strategies. The main trial limitation was early termination due to the COVID-19 pandemic, which was mitigated by inclusion of patients from an earlier pilot study. Aside from this limitation, the trial was well designed and conducted and provides convincing evidence supporting two additional defibrillation strategies; this is likely to change clinical practice. Further study should investigate DSED versus VC defibrillation to investigate which strategy is superior, as interpretation is difficult from the current study.


Cheskes S, Verbeek PR, Drennan IR, et al. Defibrillation Strategies for Refractory Ventricular Fibrillation. N Engl J Med 2022;Nov 7:[Epub ahead of print].

Editorial: Sasson C, Haukoos J. Defibrillation After Cardiac Arrest — Is It Time to Change Practice? N Engl J Med 2022;Nov 7:[Epub ahead of print].

Presented by Dr. Sheldon Cheskes at the American Heart Association Resuscitation Science Symposium, Chicago, IL, November 6, 2022.

Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: AHA Annual Scientific Sessions, AHA22, Allied Health Personnel, Arrhythmias, Cardiac, Cardiopulmonary Resuscitation, Defibrillators, Heart Arrest, Out-of-Hospital Cardiac Arrest, Patient Discharge, Return of Spontaneous Circulation, Secondary Prevention, Shock, Ventricular Fibrillation

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