title: Monophasic versus biphasic waveform shocks for atrial fibrillation cardioversion in patients with concomitant amiodarone therapy.
abstract: OBJECTIVE
  With transthoracic cardioversion of atrial fibrillation (AF), biphasic are more effective than monophasic waveforms. We sought to determine the ideal energy levels for biphasic waveforms. Methods We compared biphasic truncated exponential waveforms with monophasic damped sine waveform defibrillators, in a prospective, single-centre, randomized (1:1 ratio) study. The study included 154 patients receiving concomitant amiodarone; 77 received serial biphasic (50, 100, 150, up to 175 J) and 77 monophasic shocks (100, 200, 300, up to 360 J), as necessary. Results First-shock efficacy was similar in the two groups (57 vs. 55%, P = 0.871, respectively), as were serial-shocks (90 vs. 92%, P = 0.780). Both groups received equal numbers of shocks (1.8 +/- 1.1 vs. 1.7 +/- 1.0, P = 0.921). In both groups, serum creatine kinase levels showed a small but significant increase. The increase was, however, higher in the monophasic group.
  
  
  CONCLUSIONS
  In patients with concomitant amiodarone therapy, biphasic truncated exponential shocks, using half the energy, were as effective as monophasic damped sine shocks. The biphasic scheme was not more efficacious for cardioverting AF. In our population, a first shock of at least 100 J seemed advisable with either waveform. If necessary, escalating shocks must be performed, but ideal levels of increase per shock are still uncertain for biphasic waveforms.
authors.affiliation: Heart Institute (INCOR-HCFMUSP), University of São Paulo Medical School, Av. Doutor Enéas Carvalho Aguiar 44, 05403.000 São Paulo, Brazil.
authors.forename: Vitor S
authors.initials: VS
authors.lastname: Kawabata
authors.forename: Caio B
authors.initials: CB
authors.lastname: Vianna
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Moretti
authors.forename: Maria M
authors.initials: MM
authors.lastname: Gonzalez
authors.forename: João F
authors.initials: JF
authors.lastname: Ferreira
authors.forename: Sergio
authors.initials: S
authors.lastname: Timerman
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Cesar
mesh_terms: D000638:Amiodarone / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000628:therapy*; D016009:Chi-Square Distribution; D003131:Combined Modality Therapy; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone