BACKGROUNDPatients with recent-onset atrial fibrillation commonly undergo immediate restoration of sinus rhythm by pharmacologic or electrical cardioversion. However, whether immediate restoration of sinus rhythm is necessary is not known, since atrial fibrillation often terminates spontaneously. METHODSIn a multicenter, randomized, open-label, noninferiority trial, we randomly assigned patients with hemodynamically stable, recent-onset (<36 hours), symptomatic atrial fibrillation in the emergency department to be treated with a wait-and-see approach (delayed-cardioversion group) or early cardioversion. The wait-and-see approach involved initial treatment with rate-control medication only and delayed cardioversion if the atrial fibrillation did not resolve within 48 hours. The primary end point was the presence of sinus rhythm at 4 weeks. Noninferiority would be shown if the lower limit of the 95% confidence interval for the between-group difference in the primary end point in percentage points was more than −10. RESULTSThe presence of sinus rhythm at 4 weeks occurred in 193 of 212 patients (91%) in the delayed-cardioversion group and in 202 of 215 (94%) in the early-cardioversion group (between-group difference, −2.9 percentage points; 95% confidence interval [CI], −8.2 to 2.2; P = 0.005 for noninferiority). In the delayed-cardioversion group, conversion to sinus rhythm within 48 hours occurred spontaneously in 150 of 218 patients (69%) and after delayed cardioversion in 61 patients (28%). In the earlycardioversion group, conversion to sinus rhythm occurred spontaneously before the initiation of cardioversion in 36 of 219 patients (16%) and after cardioversion in 171 patients (78%). Among the patients who completed remote monitoring during 4 weeks of follow-up, a recurrence of atrial fibrillation occurred in 49 of 164 patients (30%) in the delayed-cardioversion group and in 50 of 171 (29%) in the earlycardioversion group. Within 4 weeks after randomization, cardiovascular complications occurred in 10 patients and 8 patients, respectively. CONCLUSIONSIn patients presenting to the emergency department with recent-onset, symptomatic atrial fibrillation, a wait-and-see approach was noninferior to early cardioversion in achieving a return to sinus rhythm at 4 weeks. (Funded by the Netherlands Organization for Health Research and Development and others; RACE 7 ACWAS ClinicalTrials.gov number, NCT02248753.

Background-Amiodarone is an effective antiarrhythmic drug rarely associated with torsade de pointes arrhythmias (TdP).The noniodinated compound dronedarone could resemble amiodarone and be devoid of the adverse effects. In the dog with chronic complete atrioventricular (AV) block (CAVB) and acquired long-QT syndrome, the electrophysiological and proarrhythmic properties of the drugs were compared after 4 weeks of oral treatment. Methods and Results-Amiodarone (nϭ7, 40 mg · kg Ϫ1 · d

Under drug-free circumstances, a persistent high BVR in chronic-AVB dogs is remodelling dependent rather than a direct consequence of bradycardia acutely after AVB. Variability of this slower rate does not influence BVR. Dofetilide causes a transient increase in BVR only in proarrhythmic dogs. Thus, BVR may aid the identification of the TdP-susceptible patient.

Background-In large mammals and humans, the contribution of I Ks to ventricular repolarization is still incompletely understood. Methods and Results-In

In the CAVB dog ventricular hypertrophy is not a prerequisite for electrical remodeling or drug-induced torsade de pointes, and the AT1-receptor has no dominant role in the completion of these remodeling processes.