To determine whether Kv1.1 deficiency leads to altered ventricular arrhythmia (VA) susceptibility, intracardiac programmed electrical stimulation (PES) was performed on adult WT (n = 29) and Kcna1‐null (KO) animals (n = 20), and ventricular responses were monitored and recorded using surface ECG and ventricular electrograms (Figure 1A‐C). The gene discussed is KCNA1; the disease is Ventricular arrhythmia.