Beta-Blocker Decreases the Increase in QT Dispersion and Transmural Dispersion of Repolarization Induced by Bepridil

Bepridil is effective for intractable cardiac arrhythmia, but in rare cases will induce torsades de pointes (TdP) associated with QT interval prolongation. Beta-blockers will effectively prevent TdP in some clinical settings, so the effect of β-blocker on the change in QT interval, QT dispersion and transmural dispersion of repolarization (TDR) induced by bepridil was investigated in 10 patients (7 male, 3 female; 62±6 years old) with intractable paroxysmal atrial fibrillation. The QTc interval, QTc dispersion and TDR were measured before and after 1 month of administration of bepridil, and then a β-blocker was added and the QTc interval, QTc dispersion and TDR re-measured 1 month later. Bepridil significantly prolonged the QTc interval (0.42±0.05 to 0.50±0.08; p