Study Overview
Objective. To assess whether immediate restoration of sinus rhythm is necessary in hemodynamically stable, recent onset (< 36 hr), symptomatic atrial fibrillation in the emergency department.
Design. Multicenter, randomized, open-label, noninferiority trial, RACE 7 ACWAS (Rate Control versus Electrical Cardioversion Trial 7--Acute Cardioversion versus Wait and See).
Setting and participants. 15 hospitals in the Netherlands, including 3 academic hospitals, 8 nonacademic teaching hospitals, and 4 nonteaching hospitals. Patients 18 years of age or older with recent-onset (< 36 hr), symptomatic atrial fibrillation without signs of myocardial ischemia or a history of persistent atrial fibrillation who presented to the emergency department were randomized in a 1:1 ratio to either a wait-and-see approach or early cardioversion. The wait-and-see approach consisted of the administration of rate-control medication, including intravenous or oral beta-adrenergic-receptor blocking agents, nondihydropyridine calcium-channel blockers, or digoxin to achieve a heart rate of 110 beats per minute or less and symptomatic relief. Patients were then discharged with an outpatient visit scheduled for the next day and a referral for cardioversion as close as possible to 48 hours after the onset of symptoms. The cardioconversion group received pharmacologic cardioversion with flecainide unless contraindicated, then electrical cardioversion was performed.
Main outcome measures. Primary outcome was the presence of sinus rhythm on electrocardiogram (ECG) recorded at the 4-week trial visit. Secondary endpoints included the duration of the index visit at the emergency department, emergency department visits related to atrial fibrillation, cardiovascular complications, and time until recurrence of atrial fibrillation.
Main results. From October 2014 through September 2018, 437 patients underwent randomization, with 218 patients assigned to the delayed cardioversion group and 219 to the early cardioversion group. Mean age was 65 years, and a majority of the patients (60%) were men (n = 261). The primary end point of the presence of sinus rhythm on the ECG recorded at the 4-week visit was present in 193 of 212 patients (91%) in the delayed cardioversion group and in 202 of 215 patients (94%) in the early cardioversion group. The –2.9 percentage points with confidence interval [CI] –8.2 to 2.2 (P = 0.005) met the criteria for the noninferiority of the wait-and-see approach.
For secondary outcomes, the median duration of the index visit was 120 minutes (range, 60 to 253) in the delayed cardioversion group and 158 minutes (range, 110 to 228) in the early cardioversion group. The median difference between the 2 groups was 30 minutes (95% CI, 6 to 51 minutes). There was no significant difference in cardiovascular complications between the 2 groups. Fourteen of 212 patients (7%) in the delayed cardioversion group and 14 of 215 patients (7%) in the early cardioversion group had subsequent visits to the emergency department because of a recurrence of atrial fibrillation. Telemetric ECG recordings were available for 335 of the 437 patients. Recurrence of atrial fibrillation occurred in 49 of the 164 (30%) patients in the delayed cardioversion group and 50 of the 171 (29%) patients in the early cardioversion group.
In terms of treatment, conversion to sinus rhythm within 48 hours occurred spontaneously in 150 of 218 patients (69%) in the delayed cardioversion group after receiving rate-control medications only. Of the 218 patients, 61 (28%) had delayed cardioversion (9 by pharmacologic and 52 by electrical cardioversion) as per protocol and achieved sinus rhythm within 48 hours. In the early cardioversion group, conversion to sinus rhythm occurred spontaneously in 36 of 219 patients (16%) before the initiation of the cardioversion and in 171 of 219 (78%) after cardioversion (83 by pharmacologic and 88 by electrical).