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Anticoagulation before cardioversion of acute atrial fibrillation in the emergency department

Three Part Question

In a patient with [acute atrial fibrillation undergoing cardioversion in the emergency department] does [anticoagulation immediately before cardioversion] [reduce the incidence of thrombo-embolism]?

Clinical Scenario

A 58 year old man presents to the emergency department with a 24 hour history of new onset AF. You decide to cardiovert him in the department (chemically or electrically) and wonder whether he needs to be anticoagulated prior to this to reduce any thromboembolic risks.

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] LIMIT to human AND English language.
Cochrane: (atrial fibrillation) AND (anticoagulation) AND (cardioversion)

Search Outcome

Altogether 54 papers were found of which non are relevant to the question.


Anticoagulation is recommended before cardioversion of AF lasting more than 2 days to avoid thromboembolic complications. However there is little evidence from the literature to support its use in AF of shorter duration.

Clinical Bottom Line

There is no evidence at present to support using anticoagulation prior to the (medical or electrical) cardioversion of new onset AF.