As cardiac safety of anti-arrhythmic drugs is of key importance, we studied how KCa2 channel inhibitors compared to two anti-arrhythmic drugs flecainide (class I, NaV1.5 inhibitor) and dofetilide (class III, KV11.1 inhibitor) under pro-arrhythmic conditions (bradycardia and hypokalemia), focusing on arrhythmia markers such as triangulation of APD, reverse-use dependence and instability [25]. This evidence concerns the gene KCNH2 and Arrhythmia.