What is the efficacy of Amiodarone (antiarrhythmic medication) for converting new-onset atrial flutter to normal sinus rhythm?

From the Guidelines

Amiodarone is a highly effective option for converting new onset atrial flutter to normal sinus rhythm, particularly in patients with underlying heart disease, due to its high success rate and low risk of proarrhythmia 1. When considering amiodarone for new onset atrial flutter conversion, several key points must be taken into account:

• Amiodarone has been shown to be more effective than other antiarrhythmic agents, such as sotalol and class I drugs, in maintaining sinus rhythm in patients with atrial fibrillation, which can be extrapolated to atrial flutter 1.
• The use of low-dose amiodarone (200 mg daily or less) may be effective and associated with fewer side effects than higher-dose regimens 1.
• Amiodarone is associated with a low risk of proarrhythmia, making it an appropriate initial choice to prevent recurrent atrial flutter in patients with left ventricular hypertrophy, heart failure, coronary artery disease, and/or previous myocardial infarction 1.
• Before initiating amiodarone therapy, baseline thyroid, liver, and pulmonary function tests should be obtained, as amiodarone can cause toxicity in these organ systems with long-term use 1.
• Patients should be monitored with continuous ECG during administration due to potential QT prolongation and risk of torsades de pointes. Some possible dosing regimens for amiodarone in this context include:
• Intravenous amiodarone as a 150 mg bolus over 10 minutes, followed by a continuous infusion of 1 mg/min for 6 hours, then 0.5 mg/min for the remaining 18 hours.
• Oral loading with 400-600 mg three times daily for 1 week, followed by 200 mg twice daily for 1-2 weeks, then a maintenance dose of 200 mg daily. It is essential to weigh the benefits and risks of amiodarone therapy in each individual patient, considering factors such as underlying heart disease, potential for toxicity, and alternative treatment options.

From the Research

Amiodarone for New Onset Atrial Flutter Conversion to Normal Sinus Rhythm

• Amiodarone is effective for long-term maintenance of sinus rhythm after electrical cardioversion of refractory atrial fibrillation or flutter 2.
• The efficacy of amiodarone for pharmacologic conversion of atrial fibrillation or flutter is related to desethylamiodarone plasma level, arrhythmia duration, left atrial area, and concomitant treatment with verapamil 2.
• Amiodarone can be used as a second-line treatment for conversion of recent-onset atrial fibrillation or flutter to sinus rhythm after ibutilide has failed, with a conversion rate of 28% 3.
• A network meta-analysis found that amiodarone likely results in a large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up for paroxysmal atrial fibrillation, with a risk ratio of 1.69 (95% CI 1.42 to 2.02) 4.
• For atrial flutter, amiodarone may result in a large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up, but the certainty of evidence is low 4.

Comparison with Other Treatments

• Amiodarone has a lower efficacy compared to bepridil and quinidine for pharmacological cardioversion of persistent atrial fibrillation 4.
• Ibutilide, propafenone, dofetilide, and sotalol may result in a large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up for atrial flutter, with moderate certainty of evidence 4.
• Flecainide and vernakalant may also result in a large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-up for atrial flutter, but the certainty of evidence is low 4.

Safety and Side Effects

• Amiodarone appears to be safe and does not have to be discontinued because of intolerable side effects 2.
• However, other antiarrhythmic drugs such as flecainide can cause rare but serious side effects, including 1:1 atrial flutter with rapid conduction and ventricular fibrillation 5, 6.