SCN5A and long QT syndrome 3: We then used these cardiomyocytes (NaV1.5 KO iPSC-CMs) to express, by simple transfection, a mutated NaV1.5 channel (NaV1.5/delQKP) associated with LQT3 and to compare it with wild-type channel-transfected cells (NaV1.5/WT).