Double Consecutive Electrical Countershock for Atrial and Ventricular Fibrillation: A Narrative Critical Review

BACKGROUND: Recent strategies for refractory ventricular fibrillation (VF) and atrial fibrillation (AF) employ two consecutive, biphasic shocks with varying evidence of success. Due to their electrophysiological similarities, the strategies used for VF and AF can be collectively referred to as double consecutive electrical countershock (DCEC). This review aims to identify and synthesize outcome data on the effectiveness of DCEC across both VF and AF. METHODS: This narrative critical review with systematic search methods was conducted in accordance with the PRISMA checklist where applicable. From 672 identified articles, 262 duplicates were removed and 410 screened; 316 articles irrelevant to the study were excluded. Of 94 sought for retrieval, 8 were unavailable and 67 failed full-text screening, leaving 19 included articles (16 VF, 3 AF). All 19 underwent risk-of-bias assessment (RoB2, ROBINS-I, or AMSTAR-2) and data extraction. RESULTS: Full-scale randomized controlled trials (RCTs) showed low risk of bias, pilot RCTs had "some concerns," observational studies carried serious risk of bias, and meta-analyses showed "low confidence." High-quality randomized evidence showed improved primary outcomes for DCEC in both refractory VF (survival to discharge, return of spontaneous circulation, good neurological outcome) and high-BMI AF (arrhythmia termination). Non-randomized observational studies predominantly showed non-statistically significant differences. CONCLUSIONS: DCEC shows potential to improve arrhythmia termination in refractory VF and high-BMI AF. Randomized evidence supports its efficacy, while observational findings remain neutral due to confounding. Success in high-BMI AF supports elevated BMI as a hypothetical indication for DCEC in VF.