Arterial fibrillation is a condition of irregular, rapid heart rate that occurs when the two upper chambers of the heart experience chaotic electrical signals. Immediate restoration of sinus rhythm using cardioversion (electrical or pharmacologic) is commonly performed, but if immediate cardioversion is necessary or not is not known. This study aims to compare the outcomes of early and delayed cardioversion in patients with recent-onset arterial fibrillation.

This is a multicenter, randomized, open-label, non-inferiority trial that included a total of 427 (212 delayed cardioversion and 215 early cardioversion) patients with hemodynamically stable, recent-onset, symptomatic arterial fibrillation. The primary outcome of the study was the presence of sinus rhythm at four weeks.

At four weeks, the presence of sinus rhythm occurred in 193 of 212 (91%) patients in the delayed-cardioversion group and 202 of 215 (94%) patients in the early-cardioversion group. In the delayed-cardioversion group, the conversion to sinus rhythm in 48 hours occurred in 150 of 212 (70%) patients, and 61 (28%) patients after delayed cardioversion. In the early cardioversion group, conversion to sinus rhythm occurred spontaneously in  36 of 215 patients (16%) and in 171 patients (78%) after cardioversion.

The research concluded that the delayed cardioversion approach in patients with recent-onset arterial fibrillation is non-inferior to early cardioversion.