608 Atrial Flutter Doesn't Cause Changes in QT Interval

Abstract

Previous studies have reported that the QT interval (QTi) increases after reversion of atrial fibrillation to sinus rhythm. Also, in patients with sequential pacemakers, the dependence of the QTi on the programmed AV interval further suggests that atrial activation influences ventricular repolarization. In order to evaluate the effect of conversion of atrial flutter to sinus rhythm on the QTi, we studied 12 patients who were submitted to a cavo-tricuspide isthmus ablation for treatment of ongoing atrial flutter. Their rhythm before, during and after the procedure was recorded with a continuous holter monitoring. For each patient, we selected periods in which the ventricular rate in atrial flutter was similat to the post-ablation sinus rate. A paired Student T test was used to compare the QTi in those periods. The mean QTi during atrial flutter was not significantly different from that in sinus rhythm (364.7 ms ± 46.4 ms and 365.8 ms ± 42.9 ms, respectively, p= 0.46). The differences of QTi in sinus rhythm and in flutter (QTi Sinus-QTi flutter) followed a normal distribution, as shown in the figure. Ventricular repolarization seems to be independent from the presence of atrial flutter when heart rates are similar.