Recommended Energy for Cardioversion of Atrial Fibrillation

Initial Energy Settings

The American Heart Association recommends starting with 50 Joules as the initial energy for atrial fibrillation using biphasic defibrillators, with a first shock success rate of 48-68% 1
The European Society of Cardiology suggests starting with 100 Joules for monophasic defibrillators 2

For biphasic defibrillators, increase energy to 75 J, then 100 J, 150 J, until a maximum of 200 J is reached 2
For monophasic defibrillators, increase energy to 150 J, 200 J, 300 J, until a maximum of 360-400 J is reached 2
Wait at least 1 minute between consecutive shocks to avoid myocardial damage 3, 4, 5

The anterior-posterior electrode configuration is generally more effective than the anterior-lateral position, with a higher overall success rate (87% vs 76%) and lower energy requirements 1, 6

Atrial fibrillation requires significantly less energy than atrial flutter, with recommended energies of 50-100 J (biphasic) or 100 J (monophasic) for atrial fibrillation, compared to 120-200 J (biphasic) or 200 J (monophasic) for atrial flutter 1, 3, 4

Identify the defibrillator type and start with the recommended energy: 50 J for biphasic (modern) or 100 J for monophasic (older) defibrillators 1, 2
Position electrodes in an anterior-posterior configuration for optimal results 1, 6

In patients with hemodynamically stable atrial fibrillation, biphasic defibrillators should be started at 120–200 J for the first shock, providing effective conversion while limiting total energy exposure. [7][8]
When only monophasic defibrillators are available, the recommended initial shock is 200 J, with escalation to 360 J if conversion fails; this approach requires substantially more cumulative energy than biphasic techniques. 8

Biphasic waveforms are markedly superior to monophasic waveforms for AF cardioversion, achieving roughly 90 % success at 200 J compared with ≈53 % for monophasic at the same energy level. 7
A biphasic shock of 200 J provides comparable efficacy to a monophasic shock of 360 J (≈91 % vs ≈85 % conversion), demonstrating the lower energy requirement of biphasic devices. 7
Biphasic cardioversion requires fewer shocks on average (1.5 vs 2.9) and a lower cumulative energy (≈203 J vs ≈570 J) than monophasic cardioversion, reducing overall energy burden. 7
Biphasic waveforms are associated with less cutaneous injury, with no reported blistering, whereas monophasic shocks carry a higher risk of dermal damage. 7