Early versus delayed cardioversion: why should we wait?

Introduction: Cardioversion (CV) is the essential component of rhythm control strategy for atrial fibrillation (AF). This review will focus on how the timing of CV affects the efficacy and safety of rhythm control strategy.Areas covered: There are no randomized studies assessing the effect of timing on CV outcome. Based on observational studies, the success of CV of acute (<48 hours) AF is consistently better than the later CV of persistent AF. Early AF recurrences are common, but early timing of CV seems to reduce recurrences. Risk of thromboembolic complications increases with the delay of CV in spite of the use of therapeutic anticoagulation. Clinically significant arrhythmic complications are rare after CV irrespective of procedure timing.Expert opinion: Based on observational studies the optimal timing of CV seems to be at 12–48 h after the onset of arrhythmic symptoms. Before proceeding to CV, the probability of early treatment failure and antiarrhythmic treatment options should be carefully evaluated to avoid the risks of repeated futile CVs. Effective anticoagulation is crucial to prevent thromboembolic complications. The first week after CV is the most vulnerable period in this respect.