Periprocedural Anticoagulation for Cardioversion of Acute Onset Atrial Fibrillation and Flutter: Evidence Base for Current Guidelines.

The practice of electrical or pharmacological cardioversion (CV) to restore sinus rhythm in patents with symptomatic atrial fibrillation (AF) or atrial flutter has been a part of clinical practice for more than 100 years. For almost as long as CV has been performed, it has been recognized that the act of restoring sinus rhythm is associated with an increased risk of stroke and systemic embolism, and that oral anticoagulant (OAC) therapy can be used to prevent peri-CV thromboembolism. Although it has been widely accepted that OAC therapy is necessary to prevent thromboembolism in patients with chronic AF/atrial flutter who undergo CV, previous clinical practice recommendations have suggested that OAC therapy may be omitted in patients at low risk of stroke. However, in recent years, evidence has emerged from several sources challenging these historical conventions. In 2018 the Canadian Cardiovascular Society AF guidelines updated the previous recommendations regarding CV of acute onset AF, and the use of peri-CV anticoagulation. In this article we present an extensive review of the evidence informing the previous recommendations, as well as the novel evidence that informed the change in recommendations. In addition, the current Canadian Cardiovascular Society AF guideline recommendations are examined within the context of contemporary international major society guidelines.