Management of Unstable Atrial Fibrillation
Immediate electrical cardioversion is the definitive treatment for unstable atrial fibrillation with severe hemodynamic compromise, intractable ischemia, or symptomatic hypotension. 1
Immediate Assessment and Intervention
Perform R-wave synchronized direct-current cardioversion immediately when atrial fibrillation causes any of the following 1:
- Ongoing myocardial ischemia unresponsive to pharmacological measures
- Symptomatic hypotension
- Angina
- Heart failure with hemodynamic instability
- Rapid ventricular response that does not respond promptly to medications
Do not delay cardioversion for anticoagulation in hemodynamically unstable patients—the immediate threat to life supersedes thromboembolic risk 1.
Special Circumstances Requiring Immediate Cardioversion
Pre-excited Atrial Fibrillation (Wolff-Parkinson-White Syndrome)
Immediate electrical cardioversion is mandatory when atrial fibrillation with pre-excitation causes rapid ventricular response with hemodynamic instability 1.
- Never use AV nodal blocking agents (adenosine, calcium channel blockers, digoxin, beta-blockers) in pre-excited atrial fibrillation, as these can paradoxically accelerate ventricular response and precipitate ventricular fibrillation 1.
- If the patient is hemodynamically stable with wide QRS complexes, intravenous procainamide or ibutilide may be attempted before cardioversion 1.
Pharmacological Management for Unstable Patients Who Cannot Undergo Immediate Cardioversion
Rate Control in Hemodynamically Compromised Patients
For patients with left ventricular dysfunction and hemodynamic compromise, use 1:
- Intravenous amiodarone (300 mg IV diluted in 250 mL of 5% glucose over 30-60 minutes) to slow ventricular response and improve left ventricular function 1, 2
- Intravenous digoxin as an alternative for rate control with improved LV function 1
For patients without clinical left ventricular dysfunction, use 1:
- Intravenous beta-blockers (esmolol 0.5 mg/kg bolus over 1 minute, then 0.05-0.25 mg/kg/min infusion) for rapid control 1, 2
- Avoid beta-blockers if bronchospastic disease or AV block is present 1
Acute Myocardial Infarction with Atrial Fibrillation
Electrical cardioversion is indicated for severe hemodynamic compromise or intractable ischemia 1.
Administer heparin to all patients with atrial fibrillation and acute MI unless contraindications exist 1.
Never use class IC antiarrhythmic drugs (flecainide, propafenone) in the setting of acute myocardial infarction 1.
Monitoring Requirements
Continuous ECG monitoring and frequent blood pressure measurement are mandatory during treatment of unstable atrial fibrillation 1, 3.
A defibrillator and emergency equipment must be readily available at the bedside 1, 3.
Common Pitfalls to Avoid
Do not attempt pharmacological cardioversion in hemodynamically unstable patients—this wastes critical time 1.
Do not delay cardioversion to achieve 3-4 weeks of anticoagulation in unstable patients 1.
Do not use digoxin or sotalol for pharmacological cardioversion, as these may be harmful 1.
Do not perform electrical cardioversion in patients with digitalis toxicity or hypokalemia, as this can precipitate ventricular arrhythmias 1.
Avoid rate-limiting calcium channel blockers (diltiazem, verapamil) in patients with pre-excited atrial fibrillation or significant left ventricular dysfunction 1.