When to defibrillate atrial fibrillation (AFib)?

From the Guidelines

Defibrillation for atrial fibrillation (AF) is recommended when the patient is hemodynamically unstable, showing signs such as hypotension, acute heart failure, or ongoing chest pain, and should be performed immediately with synchronized electrical cardioversion starting at 120-200 joules biphasic (or 200 joules monophasic) 1. For stable patients with AF lasting less than 48 hours, elective cardioversion can be performed without prior anticoagulation, as suggested by the 2018 Chest guideline and expert panel report 1. However, if AF has persisted for more than 48 hours or the duration is unknown, patients should receive at least 3 weeks of therapeutic anticoagulation before cardioversion, followed by at least 4 weeks of continued anticoagulation afterward, as recommended by the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1 and the 2016 ESC guidelines for the management of atrial fibrillation 1. Some key points to consider when deciding to defibrillate AF include:

• The duration of AF: if less than 48 hours, elective cardioversion can be performed without prior anticoagulation 1
• The patient's hemodynamic stability: if unstable, emergency cardioversion should be performed immediately 1
• The patient's stroke risk: anticoagulation should be initiated in all patients with documented AF/atrial flutter who have an increased risk of stroke, as recommended by the 2016 ESC guidelines for the management of atrial fibrillation 1
• The use of transesophageal echocardiography: can be performed to rule out left atrial thrombus before proceeding with cardioversion, but anticoagulation is still required afterward 1 The procedure should be performed under sedation (using medications like midazolam 1-2mg IV or propofol 0.5-1mg/kg IV) for elective cardioversions to minimize patient discomfort. It is also important to note that defibrillation works by delivering an electrical shock that simultaneously depolarizes all cardiac cells, allowing the sinoatrial node to resume control of the heart rhythm. Overall, the decision to defibrillate AF should be based on a careful consideration of the patient's individual circumstances, including their hemodynamic stability, stroke risk, and duration of AF, as well as the latest clinical guidelines and evidence-based recommendations 1.

From the Research

Defibrillation in Atrial Fibrillation

• Atrial fibrillation is a supraventricular arrhythmia that increases the risk of stroke and all-cause mortality 2.
• The decision to defibrillate atrial fibrillation depends on the patient's hemodynamic stability and symptoms.
• Hemodynamically unstable patients, including those with decompensated heart failure, should be evaluated and treated emergently 2.

Treatment Options

• Most hemodynamically stable patients should be treated initially with rate control and anticoagulation 2.
• Rhythm control, using medications or procedures, should be considered in patients with hemodynamic instability or in some patients based on risk factors and shared decision-making 2.
• Electrical cardioversion may be appropriate as first-line rhythm control 2.
• Pharmacologic cardioversion is a well-established alternative to electric cardioversion for hemodynamically stable patients 3.

Pharmacologic Cardioversion

• Flecainide and amiodarone are antiarrhythmic drugs that can be used for pharmacologic cardioversion 3, 4.
• A combination of amiodarone and flecainide may have additive or synergistic effects in maintaining sinus rhythm in atrial fibrillation 4.
• Pre-treatment with antiarrhythmic drugs, such as Class III AADs or amiodarone, can improve the acute restoration and maintenance of sinus rhythm after electrical cardioversion 5.

Patient Selection

• The CHA2DS2-VASc score should be used to assess stroke risk in patients with atrial fibrillation 2.
• Patients with coronary artery disease and atrial fibrillation may benefit from pharmacologic cardioversion with flecainide or amiodarone 3.
• The efficacy and safety of different treatment options should be considered on a case-by-case basis, taking into account the patient's medical history, symptoms, and risk factors 2, 3, 6.