How should I cardiovert a patient with unstable atrial fibrillation (AF) and right ventricular dysfunction (RVD)?

From the Guidelines

For a patient with unstable atrial fibrillation (AF) and right ventricular dysfunction (RVD), immediate synchronized electrical cardioversion is recommended to reduce morbidity, mortality, and improve quality of life. This approach is supported by the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation, which states that electrical cardioversion is indicated in hemodynamically unstable patients 1.

Key Considerations for Cardioversion

• Begin with 120-200 joules using a biphasic defibrillator or 200 joules with a monophasic device.
• Ensure the patient receives adequate sedation prior to cardioversion, such as midazolam 1-2 mg IV or etomidate 0.1-0.2 mg/kg IV, unless they are unconscious.
• Place pads in the anterolateral position (one below the right clavicle and one at the cardiac apex) or anteroposterior position.
• Verify the defibrillator is in synchronized mode before delivering the shock.
• If the first shock is unsuccessful, increase the energy for subsequent attempts.

Post-Cardioversion Management

• After successful cardioversion, monitor the patient closely for recurrence.
• Initiate rate control medications like beta-blockers (metoprolol 5 mg IV) or calcium channel blockers (diltiazem 0.25 mg/kg IV) as appropriate, as recommended by the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1.
• Synchronized cardioversion is preferred over unsynchronized defibrillation because it delivers the shock during the QRS complex, avoiding the vulnerable period of the cardiac cycle which reduces the risk of inducing ventricular fibrillation.

Rationale for Recommendation

The recommendation for immediate synchronized electrical cardioversion is based on the highest quality and most recent evidence available, which prioritizes the reduction of morbidity, mortality, and improvement of quality of life for patients with unstable AF and RVD 1. This approach is consistent with current guidelines and expert consensus, and is considered the best course of action for managing this condition in real-life clinical practice.

From the FDA Drug Label

Patients with specific cardiovascular conditions such as symptomatic heart failure, recent acute myocardial infarction, and angina were excluded In clinical trials of intravenous ibutilide, patients with a history of congestive heart failure (CHF) or low left ventricular ejection fraction appeared to have a higher incidence of sustained polymorphic ventricular tachycardia (VT), than those without such underlying conditions; for sustained polymorphic VT the rate was 5.4% in patients with a history of CHF and 0. 8% without it.

The patient has unstable atrial fibrillation (AF) and right ventricular dysfunction (RVD), which is similar to congestive heart failure or low left ventricular ejection fraction.

• Cardioversion with ibutilide is not recommended due to the high risk of proarrhythmia, including polymorphic ventricular tachycardia.
• The FDA drug label does not provide guidance on how to safely cardiovert a patient with these specific conditions.
• Therefore, alternative treatments should be considered, and the patient should be closely monitored with continuous ECG monitoring. 2 2

From the Research

Cardioversion of Unstable Atrial Fibrillation with Right Ventricular Dysfunction

• Emergent cardioversion is indicated in hemodynamically unstable patients with atrial fibrillation (AF) and right ventricular dysfunction (RVD) 3.
• The decision to cardiovert should be based on the patient's hemodynamic stability, with unstable patients requiring immediate intervention 3.
• For patients with AF and RVD, external direct current cardioversion remains the most common and effective method for restoration of normal sinus rhythm 4.

Energy Settings for Cardioversion

• For persistent AF, an initial energy of 200 J is recommended for biphasic defibrillators, and 300 to 360 J are recommended for monophasic defibrillators, with the electrodes placed in the anterior posterior position 4.
• A high initial energy shock, anteroposterior paddle position, and reversal of shock polarity may improve cardioversion efficacy and reduce the number of shocks required 5.

Pharmacological Cardioversion

• Pharmacological cardioversion of recent-onset AF can be a safely used, feasible, and effective approach, even in internal medicine and emergency departments 6.
• Class IC agents (flecainide or propafenone) can provide rapid conversion to sinus rhythm after either intravenous administration or oral loading, but should be used with caution in patients with left ventricular dysfunction 6.
• Intravenous amiodarone requires longer conversion times, but is still the standard treatment for patients with heart failure 6.

Rate Control

• Rate control using beta blockers or calcium channel blockers should be pursued in those with AF with RVR who do not undergo cardioversion 3, 7.
• Diltiazem likely achieves rate control faster than metoprolol, though both agents seem safe and effective 7.