Importance of beta blockade in the therapy of serious ventricular arrhythmias.

Beta blockers have traditionally been considered relatively poor antiarrhythmic agents for patients with ventricular arrhythmias. This view is based on the observations that beta blockers are less effective in suppressing spontaneous ventricular ectopy or inducible ventricular arrhythmias than are the class I and class III agents. However, there are convincing data that beta blockers can have a clinically important antiarrhythmic effect and prevent arrhythmic and sudden death. Beta blockers have multiple potential effects that can contribute to a therapeutic antiarrhythmic action, including an antiadrenergic/vagomimetic effect, a decrease in ventricular fibrillation threshold, and prevention of a catecholamine reversal of concomitant class I/III antiarrhythmic drug effects. Postinfarction trials, recent congestive heart failure studies, and observations in patients who are at risk for sustained ventricular arrhythmias all suggest a potent antiarrhythmic effect of beta blockade.