It has been reported that PD-118057, established as a selective KCNH2 current enhancer without affecting activation, confers inducibility of both ventricular tachyarrhythmia and atrial fibrillation.[8], [16] The functional similarity between this agent and circulating KCNH2-activating factor in having no significant effect on the voltage dependence of activation suggests a causal relationship of this intrinsic enhancer with arrhythmogenesis in HF. The gene discussed is KCNH2; the disease is hydrops fetalis.