Conclusion. For patients with recent-onset, symptomatic atrial fibrillation, allowing a short time for spontaneous conversion to sinus rhythm is reasonable as demonstrated by this noninferiority study.
Commentary
Atrial fibrillation accounts for nearly 0.5% of all emergency department visits, and this number is increasing.1,2 Patients commonly undergo immediate restoration of sinus rhythm by means of pharmacologic or electrical cardioversion. However, it is questionable whether immediate restoration of sinus rhythm is necessary, as spontaneous conversion to sinus rhythm occurs frequently. In addition, the safety of cardioversion between 12 and 48 hours after the onset of atrial fibrillation is questionable.3,4
In this pragmatic trial, the findings suggest that rate-control therapy alone can achieve prompt symptom relief in almost all eligible patients, had a low risk of complications, and reduced the median length of stay in the emergency department to 2 hours. Independent of cardioversion strategy, the authors stressed the importance of management of stroke risk when patients present with atrial fibrillation to the emergency department. In this trial, 2 patients had cerebral embolism even though both were started on anticoagulation in the index visit. One patient from the delayed cardioversion group was on dabigatran after spontaneous conversion to sinus rhythm and had an event 5 days after the index visit. The other patient, from the early cardioversion group, was on rivaroxaban and had an event 10 days after electrical cardiology. In order for the results of this trial to be broadly applicable, exclusion of intraatrial thrombus on transesophageal echocardiography may be necessary when the onset of atrial fibrillation is not as clear.
There are several limitations of this study. First, this study included only 171 of the 3706 patients (4.6%) screened systematically at the 2 academic centers, but included 266 from 13 centers without systematic screening. The large amount of patients excluded from the controlled environment made the results less generalizable in the broader scope. Second, the reported incidence of recurrent atrial fibrillation within 4 weeks after randomization was an underestimation of the true recurrence rate since the trial used intermittent monitoring. Although the incidence of about 30% was similar between the 2 groups, the authors suggested that the probability of recurrence of atrial fibrillation was not affected by management approach during the acute event. Finally, for these results to be applicable in the general population, defined treatment algorithms and access to prompt follow-up are needed, and these may not be practical in other clinical settings.2,5
Applications for Clinical Practice
The current study demonstrated immediate cardioversion is not necessary for patients with recent-onset, symptomatic atrial fibrillation in the emergency department. Allowing a short time for spontaneous conversion to sinus rhythm is reasonable as long as the total time in atrial fibrillation is less than 48 hours. Special consideration for anticoagulation is critical because stroke has been associated with atrial fibrillation duration between 24 and 48 hours.
—Ka Ming Gordon Ngai, MD, MPH