KCNH2 and torsades de pointes: 2006; Hancox et al. 2008) there are limitations to the extent to which nonclinical data can be linked to real‐world safety data (Valentin et al. 2010). Furthermore, blockade of hERG channels does not necessarily lead to clinically significant arrhythmias such as TdP, and not all drugs causing TdP are potent hERG blockers (Yang et al. 2001). There is also no fixed relationship between the extent of QT prolongation and the risk of TdP (Gintant 2008).