5th May 2025

Irregular narrow-complex tachycardias (i.e. atrial fibrillation)

Atrial fibrillation is the most common tachyarrhythmia in the UK. In the acute setting the priority should be on rapid pharmacological rate control of the stable patient, and then subsequent decision regarding rate vs rhythm control. There is no evidence to suggest mortality is any worse following a rate control rather than a rhythm control strategy for patients, if high-risk patients are anticoagulated. However, patients in sinus rhythm may report a better quality of life than those in AF. The mainstay of treatment in AF therefore is rate control and prevention of thromboembolic events.

Atrial fibrillation can be classified as paroxysmal (less than 7 days, then terminating), persistent (greater than 7 days, would last indefinitely unless cardioverted) and permanent (greater than 7 days, sinus rhythm not possible).

• Rate control
  • Usually with a standard beta-blocker (e.g. bisoprolol) or rate-limiting calcium-channel blocker (diltiazem or verapamil)
  • Consider digoxin if above contra-indicated
  • Amiodarone should not be used for long-term rate control
• Anticoagulation
  • Use CHA2DS2VASc and ORBIT scores to assess patient for suitability of anticoagulation
  • First-line anticoagulation for AF is a direct oral anticoagulant (DOAC) such as apixaban, dabigatran, edoxaban or rivaroxaban
  • Vitamin K antagonists such as warfarin can be used if DOACs are contraindicated

Table 6: ORBIT scoring system to assess bleeding risk when considering a patient for anticoagulation. A score of 1-2 is deemed low risk, 3 is medium risk and 4-7 high risk for a significant bleed if started on anticoagulation.

• Cardioversion
  • DCCV may be appropriate for patients presenting with fast AF if onset is within 48 hours of presentation.
  • If the history is suggestive of symptoms beginning earlier than this, or the patient is asymptomatic with no clear time of onset, cardioversion is contraindicated due to the risk of stroke from atrial thrombus formation.  
  • It is important to note that chemical cardioversion with flecainide or amiodarone carries the same risk, and therefore in patients presenting longer than 48 hours after development of AF, the management strategy should focus on rate or rhythm control, as detailed above.