Antiarrhythmic agents for chronic ventricular arrhythmias

A vast array of new antiarrhythmic agents have joined the old agents among the clinician's available resources. While treatment of ventricular arrhythmias is completely justifiable for patients with symptoms, their use to prevent sudden cardiac death has not yet been established. Because of their potential risks, the benefit/risk ratio must always be kept in mind. If we elect to treat patients who have benign or potentially lethal ventricular arrhythmias (usually to eliminate refractory symptoms) we typically begin with either a beta blocker or one of the new potent class IC antiarrhythmic agents such as flecainide or encainide. These drugs cause few side effects, no organ toxicity, and in the case of encainide or flecainide, have marked potency. Few important proarrhythmic effects are seen with these potent drugs in this group of patients. If these fail, one can try either a class IA or IB agent or a combination of a IA and IB agent. We always avoid amiodarone. In patients with lethal ventricular arrhythmias, one should choose a drug without negative inotropic potential such as quinidine or encainide as initial therapy. The combination of IA and IB agents should also be considered early in therapy. In patients with overt congestive heart failure with markedly depressed left ventricular function in the setting of lethal arrhythmias, disopyramide, beta blockers, and flecainide should be avoided. Amiodarone is used in this population only when the other available agents have proven to be ineffective or badly tolerated.