The impact of alternate defibrillation strategies on time in ventricular fibrillation

Abstract

Background: Time in ventricular fibrillation (VF) is associated with survival after out-of-hospital cardiac arrest (OHCA). The impact of vector change defibrillation (VC) and double sequential external defibrillation (DSED) on VF duration has not been explored.

Objective: To compare the effects of VC and DSED on VF duration and defibrillation outcomes.

Methods: We conducted a secondary analysis of patients enrolled in the Double Sequential External Defibrillation for Refractory VF RCT. We assessed the ECG after each shock, calculating VF time (median, IQR) and shock outcomes. The Kruskal-Wallis test was used to compare VF duration across groups, with post-hoc pairwise comparisons using Dunn's test and Bonferroni correction. Chi-square tests compared shock outcomes.

Results: Among 342 patients, 1842 shocks were analyzed (834 after three failed standard shocks: 429 standard, 218 VC, 187 DSED). Median VF time was significantly shorter for DSED (83 [0, 120] s) and VC (98 [0, 120] s) compared to standard shocks (108 [38, 120] s) (P = 0.003). The proportion of shocks leading to return of spontaneous circulation (ROSC) and survival to hospital discharge respectively was higher for DSED (17.6%, 10.2% p < 0.001 ROSC, p = 0.002 survival) and VC (14.2%, 7.3% p < 0.002 ROSC, p = 0.049 survival) than for standard shocks (5.3%, 3.5%) The proportion of shocks in which VF was not terminated was significantly lower for DSED shocks (29.9%) than standard shocks (40.6%) (P = 0.013).

Conclusions: DSED and VC reduced VF duration and increased the likelihood of ROSC and survival compared to standard shocks. These findings may contribute to the improved survival noted in the trial.

Keywords: Cardiac arrest; Cardiopulmonary resuscitation; Defibrillation; Double sequential external defibrillation; Resuscitation; Time in ventricular fibrillation; Vector change defibrillation.