Use of sedation during cardioversion with the implantable atrial defibrillator

Background-The low shock energy used during internal atrial defibrillation may decrease the need for sedation during defibrillation with an implantabl e atrial defibrillator. Methods and Results-The atrial defibrillator (Metrix Atrioverter) was impla nted in 12 patients. During the in-hospital treatment of atrial fibrillatio n (AF) episodes, intravenous sedation was given only on patient request. Th e Atrioverter was programmed for ambulatory therapy in 4 patients. Efficacy , number of shocks delivered, and sedation requirements were recorded. A to tal of 393 shocks (1.8 +/- 1.6 shocks/AF episode) were delivered to treat 2 13 AF episodes; 85 of 213 AF episodes (40%) were treated away from the hosp ital. Sinus rhythm was restored in 195 AF episodes (92%). Five patients nev er requested sedation. No sedation was needed for ambulatory-treated AF epi sodes. During the treatment of 26 of 213 AF episodes (12%), 75 shocks were delivered after patients received sedation. The number of shocks required t o treat an AF episode determined the need for sedation (4.3 +/- 2.1 shocks for AF episodes requiring sedation versus 2 +/- 1 shocks for AF episodes re quiring no sedation; P<0.001). These additional shocks were needed to treat immediate reinitiation of AF (14 episodes) or initial failure to cardiover t (4 episodes). For 8 AF episodes, sedation was requested before the first shock. Conclusions-This study suggests that, in a selected group of patients, AF c an be treated with Atrioverter therapy without sedation. Successful ambulat ory treatment of AF episodes with the Atrioverter, programmed to deliver le ss-than or similar to 2 shocks, did not require sedation. When multiple sho cks were required to treat an AF episode, the need for sedation increased a nd included patients initially not requesting sedation.