Amiodarone for Atrial Flutter
Amiodarone is a reasonable second-line option for maintaining sinus rhythm in patients with symptomatic, recurrent atrial flutter, particularly when catheter ablation is not feasible or in patients with heart failure or significant structural heart disease, but it should not be used as first-line therapy due to significant toxicity concerns. 1
Acute Management
Rate Control
- Intravenous amiodarone can be useful for acute ventricular rate control in atrial flutter patients with systolic heart failure when beta blockers are contraindicated or ineffective (Class IIa recommendation). 1
- Amiodarone is preferred in critically ill patients or those with tenuous hemodynamic stability because it has less negative inotropic effect than beta blockers, diltiazem, or verapamil and produces less hypotension. 1
- Important caveat: Amiodarone should not be used for long-term rate control in most patients due to potential toxicity. 1
- Warning: Amiodarone may convert atrial flutter to sinus rhythm, so consider anticoagulation risks in patients with flutter lasting ≥48 hours who are not adequately anticoagulated. 1
Acute Cardioversion
- Amiodarone is not a Class I recommendation for acute pharmacological cardioversion of atrial flutter—dofetilide and ibutilide are preferred agents. 1
Long-Term Rhythm Control
When to Consider Amiodarone
Amiodarone can be useful to maintain sinus rhythm in patients with symptomatic, recurrent atrial flutter (Class IIa, Level B-R), with drug choice depending on underlying heart disease and comorbidities. 1
Specific Clinical Scenarios
- Heart failure or significant structural heart disease: Amiodarone is particularly reasonable in these patients where other antiarrhythmics may be contraindicated. 1
- Refractory cases: Use amiodarone only when other treatments are contraindicated or ineffective due to significant toxicities. 1
- Contraindications to ablation: Consider amiodarone when catheter ablation cannot be performed due to underlying medical illness or patient preference. 1
Efficacy Data
- Studies show 81-87% complete suppression of atrial arrhythmias with amiodarone in refractory cases. 2, 3
- Actuarial rates for maintaining sinus rhythm: 87% at 1 year, 70% at 3 years, and 55% at 5 years. 3
- Mean maintenance dose of 268 mg/day (range 200-600 mg/day) has been effective. 4, 3
- Conversion rates during loading: approximately 18% of patients convert to sinus rhythm during a 4-week loading period. 4
Comparative Positioning
- Catheter ablation is strongly preferred (Class I recommendation) over long-term pharmacological therapy for CTI-dependent atrial flutter. 1
- Dofetilide may be more effective than amiodarone but requires inpatient initiation with renal function-based dosing and QT monitoring. 1
- Sotalol is generally better tolerated than amiodarone but carries risk of torsades de pointes. 1
Safety Considerations
Toxicity Profile
- Actuarial withdrawal rates due to adverse effects: 8% at 1 year, 22% at 3 years, 30% at 5 years. 3
- Most frequent adverse effects requiring discontinuation:
- Side effects tend to occur after prolonged treatment, not in the first 6 months. 1
Monitoring Requirements
- Average therapeutic serum concentration: 1.9 μg/mL (successfully treated patients) vs 2.3 μg/mL (patients with side effects). 2
- QTc intervals significantly prolong after amiodarone administration (from 449±88 to 508±52 ms). 5
Special Situations
Amiodarone-Induced Atrial Flutter
- Catheter ablation of the CTI is reasonable when atrial flutter develops as a result of amiodarone used for atrial fibrillation treatment (Class IIa). 1
- If flutter becomes the dominant arrhythmia, CTI ablation plus continued amiodarone can decrease flutter incidence and facilitate AF management. 1
Combination with Other Agents
- Concomitant verapamil treatment enhances conversion efficacy. 4
- Lower doses of amiodarone in combination with other antiarrhythmics may be effective and better tolerated in older patients. 6