The role of newer antiarrhythmic drugs in the management of patients with ventricular arrhythmias.

The purpose of this review is to discuss the role of mexiletine, tocainide, flecainide, and amiodarone in the treatment of patients with symptomatic ventricular ectopy or sustained ventricular tachycardia (VT) and fibrillation (VF). The pharmacologic properties, electrophysiologic effects, clinical efficacy, adverse reactions, and costs of these new agents are compared with those of procainamide, quinidine, and disopyramide. With the exception of more convenient dosing intervals, these new agents do not afford novel or advantageous pharmacologic properties. The incidences and severity of adverse reactions are similar to those reported with conventional antiarrhythmic drugs. Results of clinical studies demonstrate that these newer drugs are comparable to procainamide, quinidine, and disopyramide in suppressing ventricular ectopy. Accordingly, the choice of an antiarrhythmic agent for patients with symptomatic ventricular ectopy can be based on the side-effect profile. The propensity for developing certain adverse effects can be defined if patients are subgrouped by age and left ventricular function. The adverse effects of amiodarone preclude its use in patients manifesting only ventricular ectopy. Treatment of patients with sustained VT/VF is more complex. Mexiletine and tocainide are generally not effective. The efficacy of flecainide is similar to that of procainamide, quinidine, and disopyramide. The negative inotropic effects of flecainide and disopyramide preclude their use in patients with severe ventricular dysfunction. Amiodarone is the most effective of these drugs for preventing recurrences of sustained VT/VF. Its use should, however, be restricted to patients refractory or intolerant to other antiarrhythmic drugs.