Cardioversion for Atrial Fibrillation
Immediate Cardioversion
Proceed immediately with synchronized direct-current cardioversion if the patient is hemodynamically unstable, has ongoing myocardial ischemia, symptomatic hypotension despite rate control attempts, acute heart failure, or pre-excitation with rapid ventricular response. 1, 2
- In emergent situations, initiate IV heparin bolus followed by continuous infusion immediately, then continue oral anticoagulation for at least 4 weeks post-cardioversion 1, 2
- Use synchronized mode to deliver shock during the R wave to avoid the vulnerable period of the cardiac cycle 2
- If initial cardioversion fails, adjust electrode position, apply pressure over electrodes, or administer antiarrhythmic medication before repeating attempts 1, 2
Anticoagulation Strategy Based on AF Duration
AF Duration <48 Hours
For AF lasting less than 48 hours, initiate anticoagulation (IV heparin, LMWH, or factor Xa/direct thrombin inhibitor) as soon as possible before or immediately after cardioversion, then continue for at least 4 weeks. 1, 2
- The risk of cardioversion-related thromboembolism in this population is low (0.8%), supporting early cardioversion 3
- However, the RACE 7 ACWAS trial demonstrated that a wait-and-see approach with rate control is noninferior to immediate cardioversion, with 69% converting spontaneously within 48 hours 4
AF Duration ≥48 Hours or Unknown Duration
Anticoagulate with warfarin (INR 2.0-3.0) for at least 3 weeks before and 4 weeks after cardioversion, regardless of CHA₂DS₂-VASc score or cardioversion method. 1
- Alternative approach: perform transesophageal echocardiography to exclude left atrial thrombus, then proceed with immediate cardioversion if no thrombus is present 2, 5
- This TEE-guided strategy is particularly useful when immediate cardioversion is desired 5
Pharmacological Cardioversion Options
Patients WITHOUT Structural Heart Disease
Use flecainide, propafenone, or IV ibutilide as first-line agents for pharmacological cardioversion in patients without structural heart disease, severe left ventricular hypertrophy, heart failure with reduced ejection fraction, or coronary artery disease. 1, 2
- "Pill-in-the-pocket" approach with oral flecainide or propafenone can be used outside the hospital once safety is established, but pretreat with beta blocker or nondihydropyridine calcium channel antagonist to prevent rapid AV conduction if atrial flutter occurs 1
Patients WITH Structural Heart Disease
Use IV amiodarone for pharmacological cardioversion in patients with structural heart disease, including severe left ventricular hypertrophy, heart failure with reduced ejection fraction, or coronary artery disease. 2
- Outpatient amiodarone administration is reasonable when rapid restoration of sinus rhythm is not necessary 1
Enhancing Cardioversion Success and Preventing Recurrence
Pretreat with antiarrhythmic drugs (amiodarone, flecainide, ibutilide, propafenone, or sotalol) to enhance direct-current cardioversion success and prevent early AF recurrence. 1, 2
- If AF relapses after successful cardioversion, repeat the procedure following prophylactic antiarrhythmic medication administration 1
- Factors predicting poor long-term maintenance of sinus rhythm include prolonged AF duration, left atrial enlargement, significant mitral valve disease, and older age 6
Absolute Contraindications
Do not perform electrical cardioversion in patients with digitalis toxicity or hypokalemia. 1, 2
In pre-excited AF (WPW syndrome), avoid IV amiodarone, adenosine, digoxin, and nondihydropyridine calcium channel blockers; instead use IV procainamide or ibutilide. 1, 2
- These agents may accelerate ventricular response and precipitate ventricular fibrillation in pre-excitation 1
Long-Term Anticoagulation Decision
Base the decision about long-term anticoagulation on the patient's thromboembolic risk profile (CHA₂DS₂-VASc score), not on whether cardioversion was successful or sinus rhythm is maintained. 1