Clinical implications of new studies in the treatment of benign, potentially malignant and malignant ventricular arrhythmias

Abstract

For purposes of clinical management, ventricular arrhythmias have been divided into risk categories of benign, prognostically important (potentially malignant) and malignant. Benign arrhythmias occur in the setting of structurally normal hearts and do not require therapy unless associated with debilitating symptoms. Malignant arrhythmias such as sustained ventricular tachycardia or fibrillation deserve aggressive therapy to prevent recurrence. Arrhythmias occurring in the presence of organic heart disease (often ischemic disease) are frequently asymptomatic but prognosticaHy important as a risk factor for sudden death or cardiac arrest. The common empiric practice to treat such arrhythmias (by about 40 to 50% of cardiologists in the United States) needs to be reassessed in the face of the Cardiac Arrhythmia Suppression Trial. For malignant arrhythmias, class IA agents (procainamide and quinidine) continue to be the standard of treatment, and class IB agents (e.g., mexiletine) may be used as alternative or additive therapy. Class IC agents are used as second-line therapy, especially in the setting of ischemic heart disease. Class III therapy with amiodarone is reserved for refractory patients because of potential toxicity. Sotalol, a new class II–III agent, may become a first-line drug. For prognostically important arrhythmias, β blockers remain the agents of choice, class IC agents are contraindicated, and class IA or IB drugs, or both, should be used conservatively (i.e., only for symptomatic arrhythmias). For symptomatic but benign arrhythmias requiring treatment, β blockers are safe although not always effective. Class IA, IB and IC agents may then be considered. In these patients, the proarrhythmic potential of quinidine and class IC agents remains a concern. Better tolerated and safer drugs are needed for symptomatic arrhythmias. Some promising class I drugs under development include moricizine, pirmenol and recainam. Treatment algorithms will evolve as new study results and new drugs become available.