title: A South Australian registry of biphasic cardioversions of atrial arrhythmias: efficacy and predictors of success.
abstract: BACKGROUND
  Restoration of sinus rhythm by biphasic cardioversion is an established strategy for patients in atrial arrhythmias. This study aimed to investigate the real-life practice of cardioversions throughout a local hospital to determine frequency and predictors of success and use of high energy (> 200 joules).
  
  
  METHODS
  Prospective analysis of consecutive biphasic cardioversions from 2009-2013. Patient demographics, medical history and cardioversion data were collected.
  
  
  RESULTS
  484 cardioversions from 379 patients were included in the final analysis. The majority (73%) of cardioversions were immediately successful after a single shock; overall success was 88% (1-5 shocks). Exploratory analyses revealed that single-shock success was significantly associated with lighter weight (OR 1.19, 95% CI 1.0-1.4, p<0.05). If a second shock was required, energy escalation was significantly associated with success (OR 3.11, 95% CI 1.43-6.77, p<0.05). Increasing weight was the strongest predictor of receiving high energy (10kg increase OR 1.43, 95% CI 1.13-1.81, p<0.05).
  
  
  CONCLUSIONS
  This prospective analysis reflects the real-life heterogeneous practice of biphasic cardioversions of atrial arrhythmias throughout a local hospital. These findings highlight the importance of first shock energy selection with careful consideration of patient weight. We emphasise the recommendation to escalate energy, highlighting the need for high-energy defibrillators in 'hard-to-cardiovert' patients.
authors.affiliation: Department of Cardiology, Lyell McEwin Hospital, Haydown Road, Elizabeth Vale, South Australia, Australia 5112; University of Adelaide, Adelaide, South Australia 5005.
authors.forename: Melanie R
authors.initials: MR
authors.lastname: Wittwer
authors.affiliation: Department of Cardiology, Lyell McEwin Hospital, Haydown Road, Elizabeth Vale, South Australia, Australia 5112; University of Adelaide, Adelaide, South Australia 5005.
authors.forename: Sharmalar
authors.initials: S
authors.lastname: Rajendran
authors.affiliation: Department of Cardiology, Lyell McEwin Hospital, Haydown Road, Elizabeth Vale, South Australia, Australia 5112.
authors.forename: Jill
authors.initials: J
authors.lastname: Kealley
authors.affiliation: Department of Cardiology, Lyell McEwin Hospital, Haydown Road, Elizabeth Vale, South Australia, Australia 5112; University of Adelaide, Adelaide, South Australia 5005. Electronic address: margaret.arstall@health.sa.gov.au.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Arstall
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000628:therapy*; D001315:Australia / Q000453:epidemiology; D004554:Electric Countershock; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012042:Registries
keywords: Atrial fibrillation; Atrial flutter; Body Weight; Cardioversion; Tachyarrhythmia; Treatment efficacy