Fixed vs. incremental shock energy for atrial fibrillation: electrical cardioversion strategies in the emergency department

The optimal strategy for Electrical Cardioversion (ECV) in Atrial Fibrillation (AF) remains debated. We evaluated the impact of shock energy protocols on ECV outcomes in the Emergency Department (ED). This retrospective observational study included patients presenting with AF to the EDs in Trieste between January 2024 and April 2025. Patients undergoing ECV were classified according to initial shock energy: <200 J (incremental) or ≥200 J (fixed). Among 350 patients, overall ECV success was 92.6%, with 88.6% restoring sinus rhythm after the first shock. No significant difference in overall success was observed between incremental and fixed strategies (91.4% vs. 90.3%), although incremental energy achieved more first-shock conversions (88.1% vs. 77.4%). Magnesium sulphate premedication showed no significant association with ECV success (87.5% in patients who received magnesium vs. 93.2% in those who did not). Beta-blocker premedication was associated with lower success compared with no premedication (80% vs. 94.5%). Higher C-reactive protein levels were linked to failed cardioversion. These findings support individualized ECV strategies in the ED, with clinical judgment guiding energy selection and adjunctive therapies.