Proarrhythmia and increased mortality were noted with Class I drugs (eg, sodium channel blockers encainide, flecainide, and moricizine) in patients with post-infarction ventricular extrasystoles as shown in the CAST-1 and CAST-2 trials.5,6 D-sotalol, a Class III drug potassium channel blocker, increased mortality in the SWORD trial,7 which studied post-infarction patients with ejection fraction < 40%. This evidence concerns the gene KCNA3 and infarction.