Figure 5.

Graphs show the effects of amiodarone and two antibiotics (moxifloxacin and ciprofloxacin) on the commonly used surrogate marker for TdP risk (QTcB, % change from baseline; in blue) and on the E-M window (ms; in red). Amiodarone increased the QTcB interval, but did not decrease the E-M window; in fact, it significantly increased the E-M window and prevented induction of a negative E-M window by dofetilide. Moxifloxacin and ciprofloxacin hardly affected the E-M window despite prolongation of the QTcB interval. Graphs show mean ± SEM.