Indications for cardioversion in atrial fibrillation

There are three clinically distinct forms of atrial fibrillation:

• acute atrial fibrillation:
  • usually precipitated by an acute illness
  • sinus rhythm will often recommence when factors such as hypoxia, electrolyte abnormalities and sepsis resolve
  • NICE (1) have stated:
    • Rate and rhythm control in acute atrial fibrillation
      • carry out emergency electrical cardioversion, without delaying to achieve anticoagulation, in people with life-threatening haemodynamic instability caused by new-onset atrial fibrillation
      • In people with atrial fibrillation presenting acutely with haemodynamic instability, offer rate or rhythm control if the onset of the arrhythmia is less than 48 hours, and start rate control if it is more than 48 hours or is uncertain
      • consider either pharmacological or electrical cardioversion depending on clinical circumstances and resources in people with new-onset atrial fibrillation who will be treated with a rhythm control strategy
      • if pharmacological cardioversion has been agreed on clinical and resource grounds for new-onset atrial fibrillation, offer:
        • flecainide or amiodarone if there is no evidence of structural or ischaemic heart disease or
        • amiodarone if there is evidence of structural heart disease
      • in people with atrial fibrillation in whom the duration of the arrhythmia is greater than 48 hours or uncertain and considered for long-term rhythm control, delay cardioversion until they have been maintained on therapeutic anticoagulation for a minimum of 3 weeks. During this period offer rate control as appropriate
      • do not offer magnesium or a calcium-channel blocker for pharmacological cardioversion
• paroxysmal atrial fibrillation:
  • by definition the paroxysms of atrial fibrillation usually last less than 48 hours and hence cardioversion is not usually indicated
• chronic atrial fibrillation:
  • successful cardioversion is most likely in young patients with a structurally normal heart where the duration of atrial fibrillation is short (less than 12 months)
  • offer rate control as the first-line strategy to people with atrial fibrillation, except in people:
    • whose atrial fibrillation has a reversible cause
    • who have heart failure thought to be primarily caused by atrial fibrillation
    • with new-onset atrial fibrillation
    • with atrial flutter whose condition is considered suitable for an ablation strategy
    • to restore sinus rhythm for whom a rhythm control strategy
    • would be more suitable based on clinical judgement

Reference:

1. NICE (April 2021). Atrial Fibrillation - the management of atrial fibrillation