- Making a decision about rhythm and rate control drugs

The longer a patient remains in atrial fibrillation (AF) the greater is the likelihood of atrial thrombus developing.

In general, patients who have been in AF for longer than 48 hours should not be treated by cardioversion (electrical or chemical) until they have been fully anticoagulated for at least 3 weeks, or unless transoesophageal echocardiography has detected no evidence of atrial thrombus.

If the clinical situation dictates that cardioversion is needed more urgently, you should give:

• Either regular low-molecular-weight heparin in therapeutic dose
• Or an intravenous bolus injection of unfractionated heparin followed by a continuous infusion to maintain the activated partial thromboplastin time (APTT) at 1.5 – 2.0 times the control value

You should then continue heparin therapy and commence oral anticoagulation after successful cardioversion. It is important to seek expert advice on the duration of anticoagulation, which should be a minimum of 4 weeks, but substantially longer treatment is required in many cases.

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