New Onset Atrial Fibrillation Part 3

Symptomatic Patient

Drugs and direct cardioversion

Control rate

©      Calcium channel blockers (class I)

©      Beta blockers (class I)

©      Digoxin (class IIb)

Note:

Intravenous administration of beta blockers, digitalis, adenosine, lidocaine, and nondihydropyridine calcium channel antagonists, all of which slow conduction across the AV node, is contraindicated in patients with the WPW syndrome and tachycardia associated with ventricular preexcitation because they can facilitate antegrade conduction along the accessory pathway during AF resulting in acceleration of the ventricular rate, hypotension, or ventricular fibrillation.

Calcium channel blockers (class I)

©      Diltiazem: 0.25mg/kg over 2 minutes.  If ineffective, in 15 minutes may repeat 0.35mg/kg over 2 minutes.  Followed by a maintenance infusion of 5-15mg/hr*

©      Verapamil: 2.5 – 5mg IV over 2 minutes. May repeat with 5-10mg in 15 to 30 minutes. Maximum dose 20-30mg*

Note: Verapamil: 0.075 to 0.15 mg/kg***

In patients with decompensated HF and AF, intravenous administration of a nondihydropyridine calcium channel antagonist may exacerbate hemodynamic compromise and is not recommended. (Level of Evidence: C)

Beta blockers (class I)

Esmolol: 0.5mg/kg bolus over 1 minutes followed by an infusion at 50mcg/kg/min for 4 minutes. If no response then repeat 0.5mg/kg bolus over 1 minute and increase maintenance infusion to 100mcg/kg/min. If inadequate response in 4 minutes, repeat 0.5mg/kg bolus over 1 minute and increase maintenance infusion to 150mcg/kg/min. If inadequate response in 4 minutes, continue repeating bolus dose and increasing maintenance infusion by 50mcg/kg/min until maximum infusion of 300mcg/kg/min has been reached.

Maintenance dose: 60 to 200 mcg/kg/min IV**

Beta blockers (class I)

©      Metoprolol: 2.5 - 5mg slow IV push over 5 minutes x 3 as needed to a total dose of 15mg over 15 minutes*

©      Atenolol 5mg IV over 5 minutes; repeat 5 mg in 10 minutes if arrhythmia persists or recurs*

©      Propranolol 0.5 to 1 mg IV over 1 minute, repeated up to a total dose of 0.1 mg/kg if required*

Digoxin (class IIb)

Digoxin 8 to 12 mcg/kg total loading dose, half of which is administered initially over 5 minutes, and remaining portion as 25% fractions at 4- to 8- hour intervals*

Maintenance dose: 0.125 to 0.375 mg daily IV

Note:  Intravenous administration of digoxin or amiodarone is recommended to control the heart rate in patients with AF and HF who do not have an accessory pathway.   Digoxin is effective following oral administration to control the heart rate at rest in patients with AF and is indicated for patients with HF, left ventricular (LV) dysfunction, or for sedentary individuals.

Convert rhythm

©      Synchronized cardioversion

©      Pharmacologic cardioversion

Synchronized cardioversion

©      Atrial flutter- 50J, and increase as needed

©      Atrial fibrillation- 120 - 200 J, and increase joules as needed

Note:  Electric or pharmacologic cardioversion (conversion to normal sinus rhythm) should not be attempted in these patients unless the patient is unstable

Cardioversion may be performed electively to restore sinus rhythm in patients with persistent AF. The need for cardioversion may be immediate when the arrhythmia is the main factor responsible for acute HF, hypotension, or worsening of angina pectoris in a patient with CAD. Nevertheless, cardioversion carries a risk of thromboembolism unless anticoagulation prophylaxis is initiated before the procedure, and this risk is greatest when the arrhythmia has been present more than 48 h.  

The disadvantage of electrical cardioversion is that it requires conscious sedation or anesthesia

Anticoagulation is recommended for 3 weeks prior to and 4 weeks after cardioversion for patients with AF of unknown duration or with AF for longer than 48 hours

Pharmacologic cardioversion

©      Amiodarone

©      Procainamide

Amiodarone (IIa)

©      150 mg given over 10 minutes and repeated if necessary, followed by a 1 mg/min infusion for 6 hours, followed by 0.5 mg/min. Total dose over 24 hours should not exceed 2.2 g.*

©      Observe for bradycardia and hypotension

Note: Intravenous administration of digoxin or amiodarone is recommended to control the heart rate in patients with AF and HF who do not have an accessory pathway. (Level of Evidence: B)

Intravenous amiodarone can be useful to control the heart rate in patients with AF when other measures are unsuccessful or contraindicated. (Level of Evidence: C)

Procainamide (IIa)

©      20 to 50 mg/min* or 100 mg every 5 minutes until arrhythmia is controlled*

©      Max dose 17mg/kg.

©      Maintenance dose 1-4mg/min.

©      Observe for > 50% widening of QRS complex and hypotension

©      Avoid in patients with QT prolongation and CHF

Flecainide

©      1.5 to 3.0 mg/kg over 10 to 20 min**

©      Hypotension, atrial flutter with high ventricular rate

©      Not recommended in patients with ischemic heart disease or impaired left ventricular function

Ibutilide

©      1 mg over 10 min; repeat 1 mg when necessary**

©      QT prolongation, torsades de pointes

Propafenone

©      1.5 to 2.0 mg/kg over 10 to 20 min**

©      Hypotension, atrial flutter with high ventricular rate

©      Not recommended in patients with ischemic heart disease or impaired left ventricular function

Note:  Intravenous procainamide, disopyramide, ibutilide, or amiodarone may be considered for hemodynamically stable patients with AF involving conduction over an accessory pathway. (Level of Evidence: B)

When electrical cardioversion is not necessary in patients with AF and an accessory pathway, intravenous procainamide or ibutilide are reasonable alternatives. (Level of Evidence: C)