KCNE1 and torsades de pointes: The primary function of KCNE1 in CMs is regulating the cardiac APD.46 It serves as a major contributor to the QT interval, or the repolarization current of CMs.46 As mentioned above, KCNE1 is implicated in genetic and drug long-QT syndrome and Torsades de Pointes which are arrhythmias more common in women.47,48 These results confirm sex is an important variable to consider in pharmacological studies on hiPSC-CMs, especially for drugs that act as potassium channel blockers.