Recommended Energy Settings for Cardioversion in Atrial Fibrillation
For atrial fibrillation cardioversion, an initial energy of 200 J or greater is recommended when using monophasic waveforms, while 200 J is recommended for biphasic waveforms, particularly for patients with AF of long duration. 1
Initial Energy Settings Based on Waveform Type
Monophasic Waveform
- Initial energy should be at least 200 J for atrial fibrillation 1
- Energy should be increased successively in increments of 100 J until a maximum of 400 J is reached 1
- Higher initial energy (360 J) has shown significantly better immediate success rates (95%) compared to lower energies (14% with 100 J, 39% with 200 J) 1
Biphasic Waveform
- Initial energy of 200 J is recommended, particularly for patients with AF of long duration 1
- Lower energies are generally required compared to monophasic waveforms 1
- Median successful energy level is typically 100 J with biphasic waveform compared to 200 J with monophasic waveform 1
- For atrial flutter, initial energy may be lower (50 J) 1
Energy Recommendations Based on Arrhythmia Type and Duration
Atrial Fibrillation
- For AF ≤2 days duration: Initial energy of 100 J with biphasic waveform may be sufficient 2
- For AF >2 days duration: Initial energy of 150-200 J with biphasic waveform is recommended 2, 3
- Recent research suggests that maximum-fixed energy shocks (360 J) achieve higher first-shock success rates (75%) compared to low-escalating energy protocols (34%) 4
Atrial Flutter/Atrial Tachycardia
- Initial energy of 50 J is often sufficient for atrial flutter 1, 2
- However, starting with 100 J for atrial flutter has shown higher first-shock conversion rates (85% vs 70%) and less induction of atrial fibrillation (2% vs 11%) compared to 50 J 5
Procedural Considerations
- Allow at least 1 minute between consecutive shocks to avoid myocardial damage 1
- Synchronize the shock with the QRS complex to avoid shock delivery during the relative refractory period 1
- Select an ECG lead that clearly displays both R waves (for synchronization) and P waves (to assess outcome) 1
- Consider anterior-posterior paddle position, which has shown greater overall success (87%) compared to anterior-lateral position (76%) 1
Special Populations
Patients with Implanted Devices
- Position paddles as far as possible from implanted devices, preferably in anterior-posterior configuration 1
- Interrogate and potentially reprogram the device before and after cardioversion 1
- The risk of exit block is highest when one paddle is positioned near the impulse generator and the other over the cardiac apex 1
Common Pitfalls to Avoid
- Starting with too low energy (100 J) for atrial fibrillation with monophasic waveform, which has shown only 14% success rate 1
- Not allowing sufficient time between shocks (at least 1 minute recommended) 1
- Improper paddle placement, particularly in patients with implanted devices 1
- Failure to synchronize the shock with the QRS complex, which could induce ventricular fibrillation 1