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.