Stable atrial flutter/fibrillation

 

Algorithm - normal cardiac function

Duration < 48 hours: Control rate - calcium channel blockers or beta blockers => control rhythm - DC cardioversion or drugs (amiodarone or ibutilide or procainamide or propafenone or flecainide) Duration > 48 hours: Control rate - calcium channel blockers or beta blockers => control rhythm - no immediate DC or chemical cardioversion - delay cardioversion for 3 weeks while maintaining adequate anticoagulation, or early cardioversion (begin IV heparin at once => TEE to exclude atrial clot => cardioversion within 24 hours => anticoagulation for 4 weeks)

Algorithm - impaired cardiac function

Duration < 48 hours: Control rate - diltiazem or amiodarone or digoxin => control rhythm - DC cardioversion or amiodarone Duration > 48 hours: Control rate - diltiazem or amiodarone or digoxin => control rhythm - no immediate cardioversion - delay cardioversion for 3 weeks while maintaining adequate anticoagulation, or early cardioversion (begin heparin at once => TEE to exclude atrial clot => cardioversion within 24 hours => anticoagulation for 4 weeks)

Algorithm - WPW sydrome + normal cardiac function

Duration < 48 hours: Control rate - DC cardioversion or primary anti-arrhythmic drug (amiodarone or procainamide or propafenone or sotalol or flecanide) prn if DC cardioversion undesirable or unfeasible => control rhythm - DC cardioversion or primary anti-arrhythmic drug (amiodarone or procainamide or propafenone or sotalol or flecainide) if DC cardioversion undesirable or unfeasible Duration > 48 hours: Control rate - use primary anti-arrhythmic agents with extreme caution because of embolic risk => control rhythm - no immediate cardioversion - delay cardioversion for 3 weeks while maintaining adequate anticoagulation, or early cardioversion (begin heparin at once => TEE to exclude atrial clot => cardioversion within 24 hours => anticoagulation for 4 weeks)

Algorithm - WPW syndrome + impaired cardiac function

Duration < 48 hours: Control rate - DC cardioversion or amiodarone => control rhythm - DC cardioversion Duration > 48 hours: Control rate - use primary anti-arrhythmic agents with extreme caution because of embolic risk => control rhythm - no immediate cardioversion - delay cardioversion for 3 weeks while maintaining adequate anticoagulation, or early cardioversion (begin heparin at once => TEE to exclude atrial clot => cardioversion within 24 hours => anticoagulation for 4 weeks)

Adult doses and precautions

diltiazem is the calcium channel blocker drug of choice for rate control if the heart rate > 120 bpm diltiazem dose = 0.25mg/kg IV over 2 minutes then 0.35mg/kg IV over 2 minutes after 15 minutes if the ventricular rate still > 100 bpm => maintenance IV infusion rate of 5 - 15mg/hour verapamil dose = 2.5 - 5mg over 2 minutes IV, second dose of 5 - 10 mg in 15 - 30 minutes prn, maximum dose of 20mg  esmolol dose = IV loading dose of 0.5mg/kg over 1 minute => maintenance IV infusion rate of 50mcg/kg/min for 4 minutes => second bolus dose of 0.5mg/kg over 1 minute if response inadequate => increase maintenance infusion rate to 100mcg/kg/min for 4 minutes => repeat sequence of 0.5mg/kg bolus dose + increasing maintenance rate by 50mcg/kg/min every 4 minutes to a maximum IV infusion rate of 300mcg/kg/min metoprolol dose = 5mg IV over 5 minutes q 5 minutes x 3 prn amiodarone dose = 150mg over 10 minutes IV at 15mg/min, consider avoiding amiodarone for rate control if AF > 48 hours because of the risk of inducing chemical conversion to sinus rhythm => systemic embolisation from intra-cardia thrombi ibutilide dose = 1mg over 10 minutes IV if body weight > 60kg, 0.1mg/kg if body weight < 60kg; a second dose at the same rate may be repeated 10 minutes later prn procainamide dose = 20mg/min IV infusion to a maximum dose of 17mg/kg digoxin dose - loading dose of 10 - 15 mcg/kg by IV infusion synchronised DC cardioversion is the technique of choice for cardioversion to sinus rhythm (especially if delayed cardioversion is elected for AF > 48 hours duration) - start at 50J for atrial flutter and 100J for atrial fibrillation

Warnings

adenosine is an inappropriate drug to use because of its ultra-short action calcium channel blockers, beta blockers and digoxin are contra-indicated in WPW syndrome because they may cause a paradoxical increase in heart rate beta-blockers and verapamil are contra-indicated in patients with CHF digoxin is relatively impotent and has a slow onset of action and is no longer a preferred agent in the emergency setting - especially in paroxysmal AF and high adrenergic states IV propafenone and IV flecainide are not approved for use in the USA ibutilide use is associated with a high incidence of torsade des pointes and patients should be continuously monitored for 4 - 6 hours after ibutilide administration DC cardioversion should be used if the patient becomes clinically unstable at any time avoid using multiple anti-arrhythmic drugs serially because of their pro-arrhythmic potential