KCNH2 and chronic obstructive pulmonary disease: A gain-of-function mutation in KCNH2 has also gained recognition as a congenital disorder characterized by a higher risk for major arrhythmic events and SCD, referred to as short QT syndrome (SQT).[6], [7] It has also been reported that PD-118057, an IKr-activating agent, predisposes to cardiac arrhythmias in vitro.