KCNH2 and ventricular fibrillation: Thus, impairment of hERG function by mutations in the KCNH2 gene or by a variety of drugs prolong the QT interval of electrocardiograms leading to inherited and acquired type 2 long-QT syndrome, increasing the risk of torsade de pointes arrhythmia, ventricular fibrillation and sudden cardiac death2,8.