Amiodarone for Atrial Fibrillation with RVR: Bolus Plus Infusion is Standard
For atrial fibrillation with rapid ventricular response, amiodarone should be administered as a 150 mg IV bolus over 10 minutes followed by a continuous infusion (1 mg/min for 6 hours, then 0.5 mg/min), not infusion alone. 1, 2
Standard Loading Protocol
The FDA-approved and guideline-recommended regimen consists of three phases 2:
- Initial bolus: 150 mg IV over 10 minutes 1, 2
- Early maintenance: 1 mg/min for 6 hours (360 mg total) 1, 2
- Late maintenance: 0.5 mg/min for 18 hours (540 mg total) 1, 2
- Maximum 24-hour dose: 2.2 grams 2
This approach delivers approximately 1000 mg over the first 24 hours and has been validated in controlled clinical trials 2.
Why the Bolus Matters
The bolus provides rapid rate control and earlier cardioversion compared to infusion alone 3:
- After a 450 mg bolus, heart rate decreased from 144 bpm to 104 bpm at 30 minutes versus 116 bpm with digoxin alone 3
- Conversion to sinus rhythm occurred in 28% of patients at 30 minutes and 42% at 60 minutes following bolus administration 3
- Most conversions occur after 6-8 hours of therapy, requiring the sustained infusion component 4
The bolus-plus-infusion strategy achieves conversion rates of 55-95%, significantly higher than the 34-69% seen with bolus-only regimens 4.
Clinical Context: When Amiodarone is Appropriate
First-line agents for AF with RVR are beta-blockers or nondihydropyridine calcium channel blockers (diltiazem, verapamil), not amiodarone 1. Amiodarone is specifically indicated when 1:
- The patient has heart failure or reduced ejection fraction (where beta-blockers/calcium channel blockers may worsen hemodynamics) 1
- Other rate control measures have failed or are contraindicated 1
- Structural heart disease is present (where Class IC agents like flecainide are contraindicated) 4
Breakthrough Episodes
For recurrent VF or hemodynamically unstable VT during maintenance infusion 2:
- Administer supplemental 150 mg boluses over 10 minutes 2
- Mix in 100 mL D5W to minimize hypotension risk 2
- Do not exceed initial infusion rate of 30 mg/min 2
Critical Safety Monitoring
During bolus and infusion, continuously monitor for 1, 2:
- Hypotension (occurs in 16% of IV amiodarone patients) - slow infusion rate, add vasopressors or volume as needed 2
- Bradycardia and AV block (occurs in 4.9% with IV therapy) - slow or discontinue infusion 2
- QT prolongation - common but rarely causes torsades de pointes with amiodarone 1
Administration Requirements
Use a central venous catheter for concentrations >2 mg/mL 2. Peripheral administration at higher concentrations causes phlebitis in a high percentage of patients 2, 3. Always use 2:
- Volumetric infusion pump (not drop counters, which can underdose by 30%) 2
- In-line filter 2
- Glass or polyolefin bottles for infusions >2 hours 2
- D5W as diluent 2
Common Pitfall to Avoid
Do not use amiodarone infusion without the initial bolus in acute AF with RVR. The bolus provides immediate rate control while the infusion maintains therapeutic levels given amiodarone's long half-life (9-36 days IV) 5. Skipping the bolus delays rate control by hours and reduces overall cardioversion success 4, 3.