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Please note: this guideline has exceeded its review date and is currently under review by specialists. Exercise caution in the use of the clinical guideline.

Atrial Fibrillation (AF) or Flutter – Recent Onset

Requiring admission, or onset during admission for other problem e.g. post-surgery.

    • Follow guidance for Tachyarrhythmia.
    • Haemodynamic compromise is an indication for rapid DC cardioversion - always use sedation or general anaesthesia.
    • If the patient is haemodynamically stable (no reduced conscious level, systolic BP >90mmHg, no chest pain and no heart failure) and onset <48 hours, consider chemical cardioversion.

Chemical cardioversion

Options include:

Amiodarone IV 300mg infused over 1 hour then 900mg over 24 hours through a central line (preferable) or large peripheral line or

Flecainide IV 2mg/kg, up to 150mg, over 30 minutes if no structural or coronary heart disease.

  • Control ventricular rate with oral beta-blocker or rate-limiting calcium channel blocker (or digoxin if heart failure is present).
  • If chemical cardioversion fails, consult senior medical staff re electrical cardioversion.
  • Do echo and consider anticoagulation – see here for choice.
  • Remember – many cases of new onset AF or flutter will spontaneously revert to sinus rhythm – particularly if there is an obvious precipitating cause such as pneumonia, alcohol intoxication, hyperthyroidism or surgery.
  • Cardioversion is much less successful in established AF or flutter than in new onset, and, if being considered, should not be delayed. Anticoagulant cover required if onset >48 hours, so 4 – 6 week delay required.

Maintenance of Sinus Rhythm

Consult Cardiologist for advice. Options include beta-blocker, sotalol, flecainide and amiodarone depending upon circumstances and patient factors.

Amiodarone loading regime is amiodarone oral 200mg three times daily for 1 week then 200mg twice daily for 1 week then 200mg daily. Other oral regimens are sometimes used on the advice of a cardiologist.
N.B. Ideally, check baseline thyroid and liver function tests before starting. Interactions include digoxin and simvastatin (see BNF Appendix 1 for more details).

Figure 1 – Algorithm for Cardioversion of AF

Start enoxaparin SC 1mg/kg twice daily unless active bleeding or high risk of bleeding – Consult senior before withholding.

(For patients at extremes of body weight or eGFR <30ml/min/1.73m2 see guidelines on NHSGGC StaffNet, Clinical Guideline Electronic Resource Directory, search in 'Cardiovascular system').
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Haemodynamic compromise?

Adverse signs are: pallor, sweating, cold clammy extremities, impaired consciousness, systolic <90mmHg, pulmonary oedema, raised jugular venous pressure
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If Yes – Select here for guidance.

If No – Continue below.
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Consult with senior
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Chemical cardioversion
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IV amiodarone / IV flecainide – for dosing guidance see start of guideline.
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Chemical cardioversion failed?
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  • Onset <48 hours – Consult with senior at once re urgent DC cardioversion.
  • Onset >48 hours – Consult with senior and continue below.
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Perform echo – Excludes mitral stenosis, gives structural and functional assessment of the heart (e.g. whether LV systolic dysfunction / hypertrophy) i.e. helps identify need for anticoagulant.

N.B. Investigation should not delay treatment to slow the ventricular rate and reduce the risk of thromboembolism.

See AF – Persistent guideline for guidance on anticoagulant.
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Aim for rate control (apex <110bpm).

Beta-blocker or calcium channel antagonist are first choice. Digoxin can be added or used as first-line if signs of heart failure. See AF – Persistent guideline.

N.B. Deal with precipitants of AF: Infection, alcohol, hyperthyroidism, heart failure.