Amiodarone Topic Review

Amiodarone is a class III antiarrhythmic drug, with some class IA properties.

Amiodarone is FDA-approved only for the treatment of ventricular tachycardia, although it is most often used to maintain sinus rhythm in patients with atrial fibrillation (AF). The half-life of amiodarone is 42 days and there are significant toxicity concerns (see Amiodarone Toxicity) including thyroid, liver and lung toxicity. Due to the redistribution of the drug in the body, a significant loading dose needs to be given when the amiodarone is initiated. Likewise, due to its long half-life, the drug may still have physiologic effects even weeks after discontinuation. Intravenous amiodarone is known to cause hypotension due to the solvents used in the production process.

Amiodarone on rare occasions can induce torsades de pointes within the first 48 hours of intravenous administration, even if the QTc interval is within normal range. [Florek JB, et al. StatPearls [Internet]].

Furthermore, amiodarone may cause pulmonary toxicity, usually in the form of interstitial lung disease or hypersensitivity syndrome. [Joglar JA, et al. J Am Coll Cardiol. 2023;91a]

Guideline recommendations

The 2023 American College of Cardiology/American Heart Association/American College of Clinical Pharmacy/Heart Rhythm Society Guideline for the Diagnosis and Management of Atrial Fibrillation states that in patients with AF and rapid ventricular response rate who are critically ill and/or have decompensated heart failure (HF) and in whom beta-blockers and nondihydropyridine calcium channel blockers are contraindicated or ineffective, intravenous amiodarone may be considered (Class 2b recommendation) for acute rate control. [Joglar JA, et al. J Am Coll Cardiol. 2023;67a;102a]

The guideline also states that intravenous amiodarone is reasonable (Class 2a recommendation) to be given to patients with AF for pharmacological cardioversion, though time to conversion is usually longer (8 to 12 hours) than with other agents. [Joglar JA, et al. J Am Coll Cardiol. 2023;82a]

In addition, according to the guideline, amiodarone is reasonable (Class 2a recommendation) to be given to patients with AF and HF with reduced ejection fraction (≤ 40%) for long-term maintenance of sinus rhythm, and low-dose amiodarone (100-200 mg per day) is reasonable (Class 2a recommendation) to be given for long-term maintenance of sinus rhythm in patients with AF and normal left ventricular function, but given its side-effect profile, only for patients in whom other rhythm control strategies are ineffective, contraindicated or not preferred. [Joglar JA, et al. J Am Coll Cardiol. 2023;85a]

Amiodarone is contraindicated (Class 3 recommendation: Harm) in patients with AF with anterograde accessory pathway conduction (preexcited AF) due to risk for precipitating ventricular fibrillation or hemodynamic deterioration. [Joglar JA, et al. J Am Coll Cardiol. 2023;111a]

Use of amiodarone is reasonable (Class 2a recommendation) to reduce incidence of postoperative AF in patients at high risk for postoperative AF undergoing cardiac surgery. [Joglar JA, et al. J Am Coll Cardiol. 2023;114a]

Oral amiodarone is “not practical” for acute cardioversion because it takes several days for efficacy. [Joglar JA, et al. J Am Coll Cardiol. 2023;82a-b]

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References:

• Florek JB, et al. StatPearls [Internet]. Updated Nov. 12, 2023. Accessed May 1, 2024.

• Joglar JA, et al. J Am Coll Cardiol. 2023;doi:10.1016/j.jacc.2023.08.017.