Abstract: A method of preventing, treating, terminating and protecting against cardiac arrhythmias, such as atrial, supraventricular and ventricular ectopy, tachycardia, flutter or fibrillation, including atrial, supraventricular and ventricular arrhythmias resulting from myocardial ischemic injury in a patient in need thereof, comprising administration of a selective I.sub.Ks antagonist and a beta-adrenergic receptor blocking agent, administered in combined therapy either simultaneously, separately or sequentially is presented. Additionally, a pharmaceutical preparation comprising a selective I.sub.Ks antagonist and a beta-adrenergic receptor blocking agent, wherein these compounds are administered simultaneously, separately or sequentially is presented.