Chemical cardioversion of atrial fibrillation

Cardioversion may be achieved with drugs that stabilise the atrial myocardium, for example:

• in patients with persistent AF* ,where the decision to perform pharmacological cardioversion using an intravenous antiarrhythmic agent has been made (1):
  • in the absence of structural heart disease**, a Class 1c drug (such as flecainide or propafenone) should be the drug of choice
  • in the presence of structural heart disease**, amiodarone should be the drug of choice
    
    
• in patients with acute-onset AF (1)
  • acute AF in haemodynamically unstable patients
    • in patients with a life-threatening deterioration in haemodynamic stability following the onset of AF, emergency electrical cardioversion should be performed, irrespective of the duration of the AF
    • in patients with non-life-threatening haemodynamic instability following the onset of AF:
      • electrical cardioversion should be performed
      • where there is a delay in organising electrical cardioversion, intravenous amiodarone should be used
    • in patients with acute-onset AF with known Wolff-Parkinson-White syndrome:
      • flecainide may be used as an alternative for attempting pharmacological cardioversion
      • atrioventricular node-blocking agents (such as diltiazem, verapamil or digoxin) should not be used

Digoxin has no role in chemical cardioversion. The same precautions that are indicated in electrical cardioversion also apply to chemical cardioversion.

Remember that the antiarrhythmic drugs which are used in chemical cardioversion may themselves precipitate arrhythmias.

There is evidence that amiodarone is more effective than sotalol in maintaining sinus rhythm in patients who had had atrial fibrillation (2).

NICE state in updated guidance (3)

Cardioversion

• for people having cardioversion for atrial fibrillation that has persisted for longer than 48 hours, offer electrical (rather than pharmacological) cardioversion
  
  
• consider amiodarone therapy starting 4 weeks before and continuing for up to 12 months after electrical cardioversion to maintain sinus rhythm, and discuss the benefits and risks of amiodarone with the person
  
  
• for people with atrial fibrillation of greater than 48 hours' duration, in whom elective cardioversion is indicated
  • both transoesophageal echocardiography (TOE)-guided cardioversion and conventional cardioversion should be considered equally effective
  • a TOE-guided cardioversion strategy should be considered:
    • where experienced staff and appropriate facilities are available and
    • where a minimal period of precardioversion anticoagulation is indicated due to the person's choice or bleeding risks

Drug treatment for long-term rhythm control

If drug treatment for long-term rhythm control is needed, consider a standard beta-blocker (that is, a beta-blocker other than sotalol) as first-line treatment unless there are contraindications

If beta-blockers are contraindicated or unsuccessful, assess the suitability of alternative drugs for rhythm control, taking comorbidities into account

Dronedarone is recommended as an option for the maintenance of sinus rhythm after successful cardioversion in people with paroxysmal or persistent atrial fibrillation:

• whose atrial fibrillation is not controlled by first-line therapy (usually including beta-blockers), that is, as a second-line treatment option and after alternative options have been considered and~
  
  
• who have at least 1 of the following cardiovascular risk factors:
  • hypertension requiring drugs of at least 2 different classes
  • diabetes mellitus
  • previous transient ischaemic attack, stroke or systemic embolism
  • left atrial diameter of 50 mm or greater
  • or age 70 years or older and
    
    
• who do not have left ventricular systolic dysfunction and
• who do not have a history of, or current, heart failure

Consider amiodarone for people with left ventricular impairment or heart failure

Do not offer class 1c antiarrhythmic drugs such as flecainide or propafenone to people with known ischaemic or structural heart disease.

The summary of product characteristics should be consulted before prescribing drugs mentioned in this database.

* persistent AF does not self-terminate, or lasts longer than 7 days (without cardioversion)

**coronary artery disease or left ventricular dysfunction

Notes:

• when patients with AF are to undergo elective electrical cardioversion and there is cause for heightened concern about successfully restoring sinus rhythm (such as previous failure to cardiovert or early recurrence of AF), concomitant amiodarone or sotalol should be given for at least 4 weeks before the cardioversion

Reference:

1. NICE (June 2006). Atrial Fibrillation - the management of atrial fibrillation.
2. Kochiadakis GE et al (2000). Low dose amiodarone and sotalol in the treatment of recurrent, symptomatic atrial fibrillation: a comparative, placebo controlled study. Heart, 84, 251-7.
3. NICE (April 2021). Atrial Fibrillation - the management of atrial fibrillation.