KCNH2 and Familial short QT syndrome: On the other hand, the reduced sensitivity of IhERG inhibition by S(+) disopyramide to disruption of inactivation seen here, highlights that S(+) disopyramide may be superior to racemic disopyramide for the correction of abbreviated repolarization in SQTS patients with inactivation-attenuating hERG mutations [25, 61, 62].