title: External cardioversion of atrial fibrillation in patients with implanted pacemaker or cardioverter-defibrillator systems: a randomized comparison of monophasic and biphasic shock energy application.
abstract: OBJECTIVE
  External cardioversion (ECV) of atrial fibrillation (AF) may damage implanted pacemaker and cardioverter-defibrillator (ICD) systems. This prospective study evaluated the safety and efficacy of ECV comparing mono- to biphasic shock waveforms in patients with implanted rhythm devices.
  
  
  RESULTS
  Patients with pacemaker or ICD systems and an indication for ECV were randomized to receive mono- or biphasic shocks. Systems were tested immediately before and after ECV, 1 h and 1 week later with respect to device and lead integrity. Forty-four patients (71 +/- 10 years, 31 male; 29 pacemakers, 12 ICDs, three cardiac resynchronization systems) underwent ECV with antero-posterior paddle orientation (monophasic in 21 and biphasic in 23 patients). Pacing impedances were reduced immediately after ECV (atrial 402-392 ohm, P < 0.001; ventricular 517-496 ohm, P = 0.001) and returned to baseline values within 1 week. Ventricular sensing was reduced immediately after ECV (12.4-11.6 mV, P = 0.004). There was no device or lead dysfunction in any patient. ECV was successful in 42/44 patients (95%), cumulative energy was significantly lower for biphasic compared with monophasic shocks (P = 0.001).
  
  
  CONCLUSIONS
  ECV for AF seems to be safe and effective in patients with implanted rhythm devices.
authors.affiliation: Division of Cardiology, Department of Medicine, J. W. Goethe University Hospital, Theodor-Stern-Kai 7, Frankfurt, Germany.
authors.forename: Johannes C
authors.initials: JC
authors.lastname: Manegold
authors.forename: Carsten W
authors.initials: CW
authors.lastname: Israel
authors.forename: Joachim R
authors.initials: JR
authors.lastname: Ehrlich
authors.forename: Gabor
authors.initials: G
authors.lastname: Duray
authors.forename: Dmitri
authors.initials: D
authors.lastname: Pajitnev
authors.forename: Florian T
authors.initials: FT
authors.lastname: Wegener
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Hohnloser
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000628:therapy*; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D019544:Equipment Failure Analysis / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D016037:Single-Blind Method; D016896:Treatment Outcome