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Anticoagulation post-cardioversion of acute atrial fibrillation in the emergency department

Three Part Question

In a [patient with acute atrial fibrillation who has cardioverted to sinus rhythm] does [anticoagulation post-cardioversion] [reduce the incidence of thromboembolic complications]?

Clinical Scenario

A 45 year old man who presented to your emergency department with new onset AF has been successfully chemically cardioverted. You wonder whether he needs anti-coagulating on discharge to prevent any longer term thromboembolic complications.

Search Strategy

Medline 1966-12/04 using the OVID interface and The Cochrane Library, Issue 4, 2004.
Medline: [exp Atrial fibrillation OR OR atrial] AND [exp electric countershock OR OR exp anti arrhythmia agents OR chemical] AND [exp heparin OR OR exp heparin, low molecular weight OR low molecular weight OR fractionated OR OR OR OR OR OR OR OR OR exp warfarin or OR exp coumarins OR OR exp aspirin OR] LIMIT to human AND English language.
Cochrane: (atrial fibrillation) AND (anticoagulation) AND (cardioversion)

Search Outcome

A total of 243 papers were found, none of which answered the three part question.


It has been recommended that patients with AF lasting more than 2 days should be anticoagulated for at least one month post cardioversion. This is because of the formation of intratrial thrombus and the potential for embolic events with atrial stunning. However there is no evidence to support this approach in AF of shorter duration as the likelihood of cardioversion related thromboembolism is thought to be very low.

Clinical Bottom Line

There is no evidence to support the anticoagulation of patients with new onset AF on discharge, who have been successfully cardioverted in the emergency department (whether this be chemically, electrically, or spontaneously).