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Figures
Fig. 1
Probability of conversion to sinus rhythm at different energy levels according to type and duration of atrial tachyarrhythmias.
Fig. 2
Total cumulative shock energies under the assumption of a 2-tiered escalating shock protocol for patients with AFL/AT. The arrow lines below the bar graph indicate that, in this calculation model, all unsuccessful shocks at the initial energy setting are followed by a rescue shock of 250 J.
Fig. 3
Total cumulative shock energies under the assumption of a 2-tiered escalating shock protocol for patients with AF of various durations. The arrow lines below the bar graphs indicate that, in this calculation model, all unsuccessful shocks at the initial energy setting are followed by a rescue shock of 360 J.
Abstract
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.
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