Patients presenting to the emergency department with recent-onset atrial fibrillation (AF) do not benefit more from early cardioversion compared with a wait-and-see approach in achieving a return to sinus rhythm at 4 weeks. The results of the RACE 7 ACWAS multicentre, randomized, noninferiority trial were presented at the European Heart Rhythm Association Congress 2019, and simultaneously published in the NEJM.

Patients presenting to the hospital with symptomatic and recent-onset (<36 h) AF were randomly assigned to be managed by a wait-and-see approach (n = 218; delayed-cardioversion group) or to the standard care of early cardioversion (n = 219; early-cardioversion group). The wait-and-see approach involved the administration of rate-control medication for symptom relief; if AF was still present 48 h after symptom onset, patients were referred for cardioversion.

At the 4-week follow-up, 91% of patients in the delayed-cardioversion group and 94% of patients in the early-cardioversion group were in sinus rhythm (between-group difference −2.9 percentage points, 95% CI −8.2 to 2.2, P = 0.005 for noninferiority).

In the early-cardioversion group, 16% of patients experienced a spontaneous return to sinus rhythm before initiation of cardioversion, whereas sinus rhythm was achieved in 78% of patients who underwent cardioversion. In the delayed-cardioversion group, 69% of patients experienced a spontaneous return to sinus rhythm within 48 h, compared with 28% of patients who required cardioversion.

“The approaches to treating patients with recent-onset [AF] in the emergency department vary greatly,” remark the investigators. The RACE 7 ACWAS findings suggest that many patients with stable, symptomatic AF do not necessarily need to undergo immediate cardioversion, thus reducing the risk of potential complications.