Conclusion
The prior use of Beta blockers in addition to the antiarrhythmic medication seems to increase the risk for significant QTc prolongation following CV. A transient QTc prolongation following CV is a common finding in patients with persistent AF on antiarrhythmic medication, yet these prolongations seems to be safe without the development of sustained ventricular arrhythmia. Patients at increased risk for QTc prolongation may benefit from prolonged monitoring following CV.