SCN5A and Ventricular arrhythmia: Neither of the KCa2 channel inhibitors (AP14145 or AP30663) or flecainide (NaV1.5 inhibitor) prolonged ventricular action potential duration (APD90) or increased pro-arrhythmic markers, whereas dofetilide (KV11.1 blocker) prolonged APD and increased the susceptibility to ventricular arrhythmia.