200 J-first, fixed-escalation biphasic electrical cardioversion for atrial fibrillation >48 hours in the emergency department: a single-centre retrospective observational study

Background Guidelines permit up to 360 J for synchronised biphasic electrical cardioversion (ECV) in atrial fibrillation (AF) lasting >48 hours. The CHESS randomised trial reported higher first-shock success with fixed 360 J versus a low-escalation 125–150–200 J sequence. Much of this evidence used adhesive pads without manual pressure and anterior–posterior positioning. We evaluated a 200 J-first, fixed-escalation biphasic ECV protocol delivered with a standardised technique in an emergency department (ED). Methods Single-centre retrospective observational study of consecutive adults undergoing elective ECV for symptomatic AF >48 hours (2019–2021). Procedures used hand-held paddles with firm chest pressure in the anterolateral (AL) position under deep sedation. The predefined sequence was 200→300→360 J if needed. The primary outcome was restoration of sinus rhythm (SR) documented on a 12-lead ECG within 120 min. Secondary outcomes were first shock success at 200 J, cumulative efficacy, SR to discharge without post-ECV antiarrhythmics, adverse events and subgroup efficacy. Results were contrasted descriptively with 360 J-first cohorts (CHESS). Results Of 451 ECV procedures identified, 374 were eligible. The primary outcome was achieved in 97.3% (364/374; 95% CI 95.5 to 98.7). First-shock success with 200 J was 88.0% (329/374; 95% CI 84.3 to 90.9). Escalation to 300 J and 360 J was required in 44 and 15 patients. SR was maintained to discharge in converted patients. Two minor adverse events occurred (2/374, 0.5%) and no serious adverse events were recorded. Conclusions A 200 J-first, fixed-escalation biphasic protocol with a standardised technique (manual paddles, firm pressure, AL placement) achieved high first-shock and excellent cumulative efficacy for AF>48 hours in real-world ED care without routine pharmacologic adjuncts. Findings support considering a 200 J-first approach and motivate pragmatic multicentre randomised controlled trials directly comparing 200 J-first versus 360 J-first under harmonised technique with objective safety endpoints.