With more clinical relevant concentrations (the recommended digoxin concentrations for the treatment of chronic heart failure are around 0.8 ng/ml (1.2 nM) with a half-life of 36 hours and the toxic level is more than 2 ng/ml5, 30), we demonstrated that CGs could prolongation APD and such an effect could be attributed to the chronic effects of low concentration CGs on hERG inhibition25. The gene discussed is KCNH2; the disease is congestive heart failure.