KV 4 together with KV Channel-Interacting Protein 2 (KChIP2) mediate the fast recovering transient outward potassium current (Ito,f ) in the heart. KChIP2 is downregulated in human heart failure (HF), potentially underlying the loss of Ito,f . We investigated remodeling associated with HF hypothesizing that KChIP2 plays a central role in the modulation of outward K(+) currents in HF.