A 58-year-old man presents with new-onset chest pain and shortness of breath. ECG shows atrial fibrillation with a rate of 180 beats per minute. He has no past cardiac history. The most appropriate management would be:

e. New-onset atrial fibrillation should ideally be converted to sinus rhythm by DC cardioversion. DC cardioversion may precipitate systemic emboli from intracardiac thrombus. To avoid thromboembolic events, formal anticoagulation is required for a month before and after the cardioversion, unless:

• The arrhythmia is of less than 72 hours standing.

• No intracardiac thrombus is apparent on trans-oesophageal echocardiography.

Co-ordinated atrial activity may not resume for 2 weeks following cardioversion even if sinus rhythm is apparent on the ECG, for this reason anticoagulation should continue for 1 month usually in the form of warfarin. In this case it is inappropriate to start conservative medical management since the atrial fibrillation is of new onset (past 72 hours is cut off for cardioversion).