Timing of cardioversion in atrial fibrillation: the sooner the better?

Management of recent-onset (<36 h) atrial fibrillation (AF) in the emergency room is highly variable, particularly concerning the type and timing of cardioversion, and the logistics of the treatment pathway. In clinical practice, it is fairly common for patients with recent-onset AF an attempt at re-establishing sinus rhythm, either with electric or pharmacologic cardioversion, as soon as feasible. Nonetheless, a 'wait-and-see' approach, and potentially delayed cardioversion, could represent a valid alternative to early cardioversion, considering that, often, in recent-onset AF, sinus rhythm is re-established spontaneously, thus repealing the need for active cardioversion, hence avoiding the possible risks of treatment. These concepts form the rationale for a recent multicentric randomized trial, Rate Control vs. Electrical Cardioversion Trial 7 - Acute Cardioversion vs. Wait and See (RACE 7 ACWAS), comparing the efficacy of delayed cardioversion, within 48 h from symptoms onset, in case of lack of spontaneous conversion, with early cardioversion in symptomatic patients with recent-onset AF. In patients presenting to the emergency department with recent-onset, symptomatic AF, a wait-and-see approach was non-inferior to early cardioversion in maintaining the sinus rhythm at 4 weeks. Nonetheless a system employing a delayed cardioversion strategy increases the costs of treatment, complicates the treatment pathway, and could represent a psychological burden for the patients. Accordingly, delayed cardioversion could not represent a practical choice for many hospitals with limited resources and without an adequate outpatient organization.