title: Higher energy monophasic DC cardioversion for persistent atrial fibrillation: is it time to start at 360 joules?
abstract: BACKGROUND
  Electrical direct-current cardioversion (DCCV) has become a routine therapy for atrial fibrillation (AF), although some uncertainty remains regarding the optimal energy settings.
  
  
  OBJECTIVE
  This study examines whether the use of a higher initial energy monophasic shock of 360 joules (J) for external DCCV, in patients with persistent AF would prove more effective, yet as safe, as the use of a lower initial energy 200 J shock.
  
  
  METHODS
  A cohort of 107 patients with persistent AF was prospectively randomized to an initial synchronized DCCV shock of 360 J versus 200 J (n = 50 vs 57), followed by a similar shock sequence thereafter of four further shocks of 360 J for the two groups. In all patients the levels of troponin I (cTnI) were measured precardioversion and 18-20 hours later, the following day. In a subgroup of 36 patients in each group, the levels of creatine kinase (CK) and aspartate transaminase (AST) were measured pre- and 18-20 hours postcardioversion.
  
  
  RESULTS
  The success rate for DCCV was significantly higher in the 360 J group compared to the 200 J group (96.0% vs 75.4%, P = 0.003). The mean CK IU/L levels (1137.5.0 vs 2411.8, P = 0.014) and AST levels (39.83 vs 52.86, P = 0.010) were significantly lower in the 360 J group compared to the 200 J group. There was no statistical rise in cTnI (microg/L) in either group (P = 1.00). The average number of shocks delivered (1.84 vs 2.56, P = 0.006) was significantly less in the 360 J group than in the 200 J group, although total energy requirements for DCCV were similar for the two groups (662.4 J vs 762.4 J, P = 0.67).
  
  
  CONCLUSIONS
  For patients with persistent AF the use of a higher initial-energy monophasic shock of 360 J achieves a significantly greater success rate, with less skeletal muscle damage (and no cardiac muscle damage) as compared with the traditional starting energy of a 200 J DC shock.
authors.affiliation: St Mary's Hospital, Milton Road, Portsmouth, PO3 6AD, UK. christopherboos@hotmail.com
authors.forename: C
authors.initials: C
authors.lastname: Boos
authors.forename: M D
authors.initials: MD
authors.lastname: Thomas
authors.forename: A
authors.initials: A
authors.lastname: Jones
authors.forename: E
authors.initials: E
authors.lastname: Clarke
authors.forename: G
authors.initials: G
authors.lastname: Wilbourne
authors.forename: R S
authors.initials: RS
authors.lastname: More
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000628:therapy*; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016037:Single-Blind Method