In the hypertrophic ventricular myocardium in animal models of cardiac hypertrophy or patients with organic heart disease, especially in patients with co-existing heart failure and myocardial injury, the expression of Kv4.3 and Kv4.2 in ventricular myocytes is downregulated and the activity of Ito channels is reduced. This evidence concerns the gene KCND3 and heart disorder.