Introduction

Atrial fibrillation (AF) is the most frequently encountered dysrhythmia seen in the United States, both in the outpatient and emergency department (ED) settings.1 In 2014 in the United States, over half a million people visited EDs for AF, leading to a 62% admission rate and $10.1 billion in adjusted annual charges for admitted patients.2
The treatment of patients presenting with AF is dependent upon several factors including the patient’s hemodynamic status and the time of onset. If the patient presents when hemodynamically unstable, immediate conversion to sinus rhythm is required despite the time of onset of AF. For hemodynamically stable patients the issue then becomes rate and rhythm control. Rhythm control in the ED, whether by electrical or pharmacologic means is acceptable for those who have been anticoagulated for at least three weeks or if the atrial fibrillation is known to have started less than 48 hours.3 The “48-hour rule” that has been implemented in clinical practice is based on theoretical rather than evidence-based data. The risk of thromboembolism in patients undergoing cardioversion for AF of <48 hours duration is extremely low and ranges between 0-0.9%. However, cardioversion of patients with AF >48 hours’ duration without prior adequate anticoagulation led to a 5-7% risk of stroke thus leading to the 48-hour rule.4 Cardioverting patients (electrically or pharmacologically) who present to the emergency department with AF of less than 48 hours’ duration can be done safely and effectively by emergency physicians.5–8
Current guidelines for those with AF more than 48 hours and not on anticoagulation recommend either rate control and discharge from the ED on anticoagulation for at least 3 weeks before and at least 4 weeks after cardioversion, or performance of a transesophageal echocardiogram (TEE) with subsequent cardioversion if there is no clot on the atria or left atrial appendage.3
The objective of this study is to describe the safety and efficacy of a clinical pathway for patients who presented to the ED with AF >48 hours, who underwent TEE, and then had synchronized electrical cardioversion performed in the ED versus the cardiology department. Major outcomes included time to cardioversion and length of hospital stay. Secondary outcomes included the rate of successful cardioversion, complications, and readmissions within 30 days of hospital discharge.