KCNH2 and Ventricular arrhythmia: Since several widely used drugs (e.g. terfenadine, astemizole, and cisapride) with HERG/IKr-blocking properties had to be withdrawn from the market due to the occurrence of lethal ventricular arrhythmia [2], [12], all novel candidate drugs have to be screened for HERG/IKr-blocking properties in vitro and in vivo at an early stage of drug development [13].