Background: Atrial fibrillation is the most common type of cardiac arrhythmia and is associated with elevated rates of stroke, heart failure, hospital admission, and death. Its prevalence in the overall population is 1.5% to 2%. To convert atrial fibrillation to sinus rhythm, cardioversion is needed.
Methods: This review is based on pertinent articles published from 2004 to December 2014 that were retrieved by a selective PubMed search employing the terms "atrial fibrillation" and "cardioversion."
Results: In electrical cardioversion, a defibrillator is used to pass a pulse of current between two electrodes. In pharmacological cardioversion, antiarrhythmic drugs are given intravenously or orally. Electrical cardioversion results in sinus rhythm in more than 85% of patients; pharmacological cardioversion results in sinus rhythm in about 70% of patients with recent-onset atrial fibrillation. As a rule, cardioversion should be carried out only under effective therapeutic anticoagulation with heparin, a vitamin K antagonist, or a new oral anticoagulant drug. If atrial fibrillation has been present for more than 48 hours, cardioversion must be preceded by transesophageal echocardiography to rule out blood clot in the left atrium, or else the patient is pretreated with an anticoagulant drug for at least 3 weeks. As cardioversion can transiently impair left atrial pumping function, anticoagulation is usually maintained for 4 weeks after the procedure. The decision whether to continue anticoagulation beyond this point is based on the risk of stroke, as assessed with the CHA2DS2-VASc score.
Conclusion: The main risks of cardioversion-thrombo--embolism and clinically significant hemorrhage--occur in 1% of cases or less (in the first 30 days after treatment) if the procedure is carried out as recommended in therapeutic guidelines. Serious complications still occur, but they are rare.