Congenital long QT syndrome can lead to

Polymorphic VT has a continually changing QRS morphology indi- cating a changing ventricular activation sequence. Polymorphic VT that occurs in the context of congenital or acquired prolongation of the QT interval often has a waxing and waning QRS amplitude creat- ing a "twisting about the points" appearance referred to as Torsade de Pointes Ref Harrison 20th edition pg 1445