The concurrent inhibition of INa may offset repolarization prolongation caused by hERG inhibition or even result in QT shortening, as well as QRS widening, conduction disturbances, and conduction slowing (PR-interval prolongation, AV block, bundle branch block), as was shown in the rabbit wedge study and in anesthetized guinea pigs. The gene discussed is KCNH2; the disease is bundle branch block.