Prevention of Torsade de Pointes during the Pharmacologic Treatment of Atrial Fibrillation

Potassium channel blockers are sometimes effective in the rhythm management of persistent atrial fibrillation. However, on rare occasions, a life-threatening episode of torsade de pointes develops during treatment with these agents. Among several precautions against this tragedy, preventing exaggerated QT prolongation is of paramount importance. One of the difficulties in monitoring the QT interval during atrial fibrillation is the fact that its length varies depending not only on the fluctuating preceding intervals, but on other factors such as neurohumoral activation. In fact, even at the same preceding RR interval, the QT interval may vary from day to night, between atrial fibrillation and sinus rhythm. Accordingly, the QTc interval may not be a reliable parameter for predicting proarrhythmic events. As the result, close monitoring of the QT interval itself, just like INR monitoring during warfarin treatment, is mandatory both before and during treatment with these agents.