"A Randomized Trial Assessing the Effect of Early Double Sequential Defibrillation With Anterior-posterior and Anterior Lateral Pad Placement and Sequential Defibrillation Compared to Standard Pad Placement and Single Defibrillation in Patients With Out of Hospital Cardiac Arrest With Initial Shockable Rhythm and at Least One Failed Standard Defibrillation"

Background: Out-of-hospital cardiac arrest (OHCA) affects about 270,000 individuals in Europe annually.[1] In OHCA, presenting with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) amendable to defibrillation are among the strongest predictors of survival.[2] If defibrillation can be done successfully within the first 3-5 minutes survival can be as high as 70 %.[3] However, some patients in VT/VF do not respond to initial defibrillation, and survival decreases with number of defibrillations required to terminate VT/VF.[4]

In 2022, one prospective cluster randomized trial showed increased survival among OHCA patients in refractory VF using an alternative defibrillation strategy with either, switching to Anterior-Posterior defibrillation pad placements (A-P) or Double Sequential Defibrillation "DSD", (Using two defibrillators, one in the standard anterior-lateral position (A-L) and one in A-P position and defibrillation in rapid sequence) compared to standard defibrillation pad placement.[5] Refractory VF was defined as VF that persisted despite three consecutive defibrillations with defibrillation pads in the standard position.

These results prompted the International Liaison Committee on Resuscitation (ILCOR) to release a statement of treatment recommendation on DSD in March 6, 2023. It suggested that "…either vector change or DSD may be considered for adults with cardiac arrest who remain in VF or pulseless VT despite three defibrillations (weak recommendation, low certainty of evidence)." [6] Further, if DSD would be used it should be performed with a methodology similar to that described in the trial by Cheskes et al.

However, several questions remain. Knowledge gaps highlighted in the ILCOR statement included if the results from this one cluster randomized trial could be reproduced in any other setting. Further, since survival is inversely associated with the number of defibrillation shocks, if earlier application of DSD could lead to even higher survival for patients not in refractory VF has never been studied.

Study rationale: In order to evaluate if an early DSD-strategy could benefit all patients with VT/VF after the first shock, including those not in refractory VF, the Double-D trial is designed. If DSD would prove to be superior to standard defibrillation in a broader cardiac arrest population, also among those not in refractory VF, this would have a large impact on how Advanced Cardiac Life Support (ACLS) should be performed.