Rhythm control in atrial fibrillation (AF) improves haemodynamic status and symptoms. However, there are few data related to revisit of patients who have undergone cardioversion in the Emergency Department (ED). The aim of the study was to compare ED revisit within 30 days according to the effectiveness of cardioversion and analyse the variables related to effective cardioversion. We undertook a multicentre, observational, cohort study with a 30-day follow-up. Older adults with AF presenting to 5 EDs in Spain and undergoing cardioversion were included. The primary endpoint was revisit to the ED within 30 days, and univariate and multivariate analyses were carried out according to the effectiveness of cardioversion. We enrolled 336 patients who underwent cardioversion in the ED. Following the index visit, 7.4% revisited the ED within 30 days, with no differences with respect to the effectiveness of cardioversion (hazard ratio: 0.87; 95%confidence interval (CI) 0.31–2.43). In the multivariate study, AF lasting <48 hours was related to more effective cardioversion (adjusted odds ratio (aOR): 2.14; 95% CI 1.16–3.59) while the use of amiodarone (aOR: 0.52; 95% CI 0.27–0.99) and digoxin in ED (aOR: 0.28; 95% CI 0.13–0.66) was related to less effective cardioversion. In patients with AF undergoing a rhythm control strategy in the ED, the absence of restoration of sinus rhythm was not associated with a greater frequency of 30-day ED revisit.