Atrial fibrillation has progressively become a more common reason for emergency de-partment visits, representing 0.5% of presenting reasons. Registry data have indicated that about 60% of atrial fibrillation patients who present to the emergency department are admitted, emphasizing the need for more-efficient management of atrial fibrillation in the acute phase. Management of atrial fibrillation in the setting of emergency department varies between countries and health care systems. The most plausible reason to justify a conservative rather than aggressive strategy in the management of atrial fibrillation is the absence of specific guidelines from diverse societies. Several trials of atrial fibrillation treatment strategies, including cardioversion, have demonstrated that atrial fibrillation in emergency department can be treated safely and effectively, avoiding admission. In the present study, we review the epidemiology and characteristics of atrial fibrillation pa-tients presenting to the emergency department will be reviewed, as well as the impact of diverse management strategies on atrial fibrillation-related hospital admissions. Lastly, the design and initial data of the HEROMEDICUS protocol, which constitutes an elec-trophysiology-based aggressive rhythm control strategy in patients with atrial fibrillation in the emergency department setting will be presented.