Patients with malignant or potentially malignant ventricular arrhythmias: opportunities and limitations of drug therapy in prevention of sudden death.

Almost 90% of patients resuscitated from out of hospital cardiac arrest have coronary heart disease and can be categorized in one of three groups: acute myocardial infarction, ischemic event or primary arrhythmic event. The patients who have acute myocardial infarction have the best prognosis, and those with primary arrhythmic events have the worst. Recent studies show that ventricular arrhythmias after myocardial infarction are associated with mortality independent of any association with left ventricular dysfunction. Ventricular arrhythmias that have caused cardiac arrest or hemodynamic collapse, that is, malignant arrhythmias, should be treated aggressively and evaluated carefully with one of two methods that have high predictive accuracy for outcome: 1) the Holter recording/exercise test approach, or 2) the electrophysiologic approach. It is not yet known whether treating potentially malignant ventricular arrhythmias after myocardial infarction with class I or III antiarrhythmic drugs will reduce mortality, but two clinical trials are under way in the United States to address this question. Beta-adrenergic blocking drugs do reduce mortality, probably as a result of both antiischemic and antiarrhythmic effects. Calcium channel blocking agents, various antiplatelet drugs and alpha-adrenergic blocking drugs are under investigation to determine their value in secondary prevention of ventricular fibrillation.