Congenital long QT syndrome can lead to -

Long QT syndrome (LQTS) is a rare congenital and inherited or acquired hea condition in which delayed repolarisation of the hea following a heabeat increases the risk of episodes of torsades de pointes (TdP, a form of irregular heabeat that originates from the ventricles ). These episodes may lead to fainting and sudden death due to ventricular fibrillations . Episodes may be provoked by various stimuli Ref Harrison 20th edition pg 1445