Optimization of initial energy for cardioversion of atrial tachyarrhythmias with biphasic shocks

Am J Emerg Med. 2010 Feb;28(2):159-65. doi: 10.1016/j.ajem.2008.10.028.


Objective: Recommendations for optimal first-shock energies with biphasic waveforms are conflicting. We evaluated prospectively the relation between type and duration of atrial tachyarrhythmias and the probability of successful cardioversion with a specific biphasic shock waveform to develop recommendations for the initial energy setting aiming at the lowest total cumulative energy with 2 or less consecutive shocks.

Methods: We analyzed 453 consecutive patients undergoing their first transthoracic electrical cardioversion, including 358 attempts for atrial fibrillation (AF) and 95 attempts for atrial flutter (AFL) or atrial tachycardia (AT). A step-up protocol with a truncated exponential biphasic waveform starting at 50 J was used. Total cumulative energies were estimated under the assumption of a 2-tiered escalating shock protocol with different initial energy settings and a "rescue shock" of 250 J for AFL/AT or 360 J for AF. The initial energy setting leading to the lowest total cumulative energy was regarded as the optimal first-shock level.

Results: Cardioversion was successful in 448 patients (cumulative efficacy, 99 %). In patients with AFL/AT, the lowest total cumulative energy was attained with an initial energy setting of 50 J. In patients with AF, lowest values were achieved with an initial energy of 100 J for arrhythmia durations of 2 days or less and an initial energy of 150 J for arrhythmia durations of more than 2 days.

Conclusion: We recommend an initial energy setting of 50 J in patients with AFL/AT, of 100 J in patients with AF 2 days or less, and of 150 J with AF more than 2 days.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Atrial Fibrillation / therapy*
  • Atrial Flutter / therapy*
  • Electric Countershock / methods*
  • Female
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Prospective Studies
  • Recurrence
  • Tachycardia, Ectopic Atrial / therapy*