Does amiodarone (antiarrhythmic medication) impair cardiac output?

From the Guidelines

Amiodarone does not significantly impair cardiac output, particularly in patients with heart failure, as evidenced by recent guidelines. This is supported by the 2016 ESC guidelines for the management of atrial fibrillation, which state that amiodarone is safe in patients with heart failure 1. The guidelines highlight that amiodarone is an effective multichannel blocker that reduces ventricular rate and is safe for use in patients with heart failure.

Key points to consider when prescribing amiodarone include:

• Its effectiveness in reducing ventricular rate and managing atrial fibrillation
• The potential for extracardiac side effects, especially with long-term therapy
• The importance of monitoring QT interval and TU waves due to the risk of torsades de pointes pro-arrhythmia
• The suitability of amiodarone as a second-line treatment due to its side effect profile

In contrast to older studies, more recent evidence suggests that amiodarone's negative inotropic effects are not clinically significant, especially at lower doses. For example, a study from 2001 suggested that amiodarone has no clinically relevant negative inotropic effects 1. However, this study is older and less relevant than the 2016 guidelines.

When initiating amiodarone, particularly in patients with compromised cardiac function, close monitoring of hemodynamic parameters is still essential to ensure that any potential negative effects on cardiac output are promptly identified and managed. The benefits of amiodarone in improving rhythm control and reducing arrhythmia-related morbidity and mortality should be weighed against its potential risks, and clinicians should consider the individual patient's condition and medical history when making treatment decisions 1.

From the FDA Drug Label

Fentanyl: (CYP3A4 substrate) in combination with amiodarone may cause hypotension, bradycardia, and decreased cardiac output.

Amiodarone may impair cardiac output, particularly when used in combination with other medications such as fentanyl. The FDA drug label warns of potential hypotension, bradycardia, and decreased cardiac output when amiodarone is used with fentanyl 2.

• Key points:
  • Amiodarone may cause decreased cardiac output
  • Combination with fentanyl may increase risk of hypotension, bradycardia, and decreased cardiac output
  • Close monitoring is recommended when using amiodarone with other medications that may affect cardiac function.

From the Research

Effects of Amiodarone on Cardiac Output

• Amiodarone can impair cardiac function due to its intrinsic negative inotropic properties, as seen in animal studies and most human studies with intravenous administration 3.
• The drug induces dose-related negative inotropic effects, in addition to coronary and systemic vasodilatation and slowing of the heart 3.
• In patients with pre-existing ventricular dysfunction, cardiac pump function is impaired further when relatively high dosages of amiodarone are used without its solvent Tween 80 3.
• Fast bolus administrations of amiodarone can result in an improvement of cardiac output, albeit at the expense of an increase in left ventricular filling pressure 3.
• However, when given by mouth, amiodarone does not have significant hemodynamic effects, other than a moderate reduction in heart rate and, occasionally, in diastolic blood pressure 3.
• Cardiac pump function is not affected by oral amiodarone, even in patients with ventricular dysfunction or heart failure, in whom chronic oral administration of the drug is well tolerated 3.

Comparison with Other Antiarrhythmic Agents

• A study comparing the effects of antiarrhythmic agents on myocardial performance found that intravenous amiodarone and sotalol impair contractility and cardiac output, but procainamide does not 4.
• Amiodarone decreased cardiac output and worsened diastolic function in isolated hearts, while procainamide did not have a significant effect on any measures of systolic or diastolic performance 4.
• The use of amiodarone is regularly accompanied with QT and QTc-interval prolongation but rarely with ventricular proarrhythmia, and it can be safely used in patients with left ventricular dysfunction after myocardial infarction or those with congestive heart failure or hypertrophic cardiomyopathy 5.

Clinical Considerations

• Amiodarone is a potent coronary and peripheral vasodilator and can be used in patients with complex cardiac arrhythmias, but its use requires careful consideration of its potential side effects and interactions with other medications 5, 6, 7.
• Clinicians must be aware of the appropriate use, follow-up, and adverse reactions of amiodarone, and patients treated with the drug require close supervision 6, 7.