Alternative Defibrillation Strategies for Refractory Ventricular Fibrillation: A Systematic Review and Meta-Analysis

Background Cardiac arrest with refractory ventricular fibrillation (rVF) represents a dramatic medical emergency. Despite recent advances, its treatment is challenging and burdened by limited evidence. This systematic review and meta-analysis aims at establishing whether alternative defibrillation strategies (ADS), i.e. double sequential external defibrillation (DSED) or vector-change defibrillation (VCD), improve survival among patients with rVF compared to standard defibrillation (SD). Methods Randomized clinical trials (RCTs), prospective and retrospective studies were included if: (1) compared ADS with SD in rVF; (2) conducted on patients ≥ 18 years old; (3) reported survival to hospital admission. English-language papers from MEDLINE, Google Scholar, Cochrane Library, World Health Organization, EMBASE and CINAHL, published from inception to December 2022, were retrieved. The risk of bias was assessed following the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies and the revised Cochrane risk of bias tool for randomized trials, as appropriate. A random-effects meta-analysis was performed to estimate the pooled Odds Ratio (pOR) with 95% Confidence Interval (95%CI) of ADS and survival to hospital admission. Furthermore, a subgroup analysis was performed to compare SD with each type of ADS. The protocol was registered on PROSPERO (CRD42022379049). Results Eight studies (2 RCTs, 5 retrospective and 1 case-control study) were retrieved for qualitative and quantitative analyses. The study population included 1405 patients (ADS = 493 vs. SD = 912) with a pooled mean age of 61.9 ± 1.1 years; among them, 277 (19.7%) were female. The random-effect meta-analysis did not show differences in survival to hospital admission among ADS vs. SD (pOR = 1.12, 95%CI: 0.62-2.01). The subgroup analysis confirmed that neither DSED (pOR = 1.20, 95%CI: 0.56-2.58) nor VCD (pOR = 1.66, 95%CI: 0.10-27.02) were associated with improved survival to hospital admission. Main limitations were: i) few numbers of studies included with small sample size; and ii) female under-representation. Conclusion The present manuscript did not show any difference on survival to hospital admission between the considered defibrillation strategies in rVF. This result highlights the need for further ad hoc clinical trials assessing the actual role of ADS.