Amiodarone Administration After Cardioversion of Atrial Fibrillation
After successful cardioversion of atrial fibrillation to sinus rhythm, amiodarone should be started as a maintenance infusion rather than given as a bolus dose. 1
Evidence-Based Rationale
The FDA-approved amiodarone dosing regimen for intravenous administration clearly outlines a structured approach that begins with an initial loading dose followed by maintenance infusion 1. While the initial loading dose (150 mg over 10 minutes) is appropriate when starting treatment, after successful cardioversion to sinus rhythm, the maintenance phase is the appropriate next step.
Maintenance Infusion Protocol
After cardioversion to sinus rhythm, the recommended approach is:
- Start a maintenance infusion at 0.5 mg/min (720 mg per 24 hours)
- Use a concentration of 1-2 mg/mL for peripheral access (or up to 6 mg/mL with central venous access)
- Continue this maintenance infusion to maintain sinus rhythm 1
Why Avoid Additional Bolus Doses
Additional bolus doses after successful cardioversion carry several risks:
- Increased risk of hypotension (a common adverse effect leading to discontinuation)
- Higher potential for bradycardia and AV block
- Unnecessary exposure to higher drug concentrations when rhythm has already been restored 1
Clinical Context
The 2014 AHA/ACC/HRS guidelines for atrial fibrillation management indicate that amiodarone is reasonable for pharmacological cardioversion (Class IIa, Level of Evidence A) 2. However, once cardioversion has been successful, the goal shifts to maintenance of sinus rhythm, which is best achieved through a steady-state concentration provided by continuous infusion.
Safety Considerations
When administering amiodarone infusions:
- Use a volumetric infusion pump to ensure accurate dosing
- For infusions longer than 1 hour, do not exceed concentrations of 2 mg/mL unless using a central venous catheter
- Monitor for hypotension, bradycardia, and QT prolongation 1
Transition to Oral Therapy
If long-term maintenance of sinus rhythm is desired:
- Begin oral amiodarone therapy while continuing IV infusion
- The European Society of Cardiology guidelines suggest starting oral therapy 1-3 days before cardioversion when planning maintenance therapy 2
- Adjust oral dosing based on duration of IV therapy already administered 1
Important Caveats
- Amiodarone shows considerable interindividual variation in response, requiring close monitoring
- For patients with structural heart disease or left ventricular dysfunction, amiodarone is preferred over class IC agents like flecainide or propafenone 3
- Regardless of rhythm control success, anticoagulation should be continued in patients with stroke risk factors 3
By following this approach of using maintenance infusion rather than additional bolus doses after successful cardioversion, you can optimize efficacy while minimizing the risk of adverse effects associated with high peak concentrations of amiodarone.