Remimazolam for Procedural Sedation During Synchronized Electrical Cardioversion in the Emergency Department

Synchronized electrical cardioversion necessitates procedural sedation to ensure patient comfort and amnesia. Remimazolam is a novel, ultrashort-acting intravenous benzodiazepine with organ-independent esterase metabolism, a favorable safety profile, and flumazenil reversibility. Although, previously described in the electrophysiology laboratory, use of remimazolam has not been reported for electrical cardioversion in the emergency department. In this case, a 67-year-old man with sudden-onset paroxysmal atrial fibrillation presented in symptomatic atrial fibrillation with rapid ventricular response. Following rate and rhythm optimization, the decision was made to proceed with synchronized electrical cardioversion under procedural sedation. After consent was obtained, remimazolam (5 mg intravenously) was administered as a single bolus. Sedation onset occurred at 49 seconds, with adequate depth achieved at 1 minute 37 seconds. A single synchronized biphasic 200 joule electric shock was successfully delivered at 2 minutes 20 seconds, converting the patient to normal sinus rhythm. Eye opening occurred at 3 minutes 50 seconds, with return to baseline orientation at 4 minutes 30 seconds. No apnea, hypoxia, hemodynamic instability, or procedural recall was observed. Continuous end-tidal carbon dioxide monitoring confirmed uninterrupted spontaneous ventilation throughout. The rapid onset, hemodynamic stability, and remarkably brief recovery time observed support its potential as a first-line sedative for emergency department cardioversion. Further prospective study in this setting is warranted.