MODULATION OF ANTIARRHYTHMIC DRUG EFFECTS BY BETA-ADRENERGIC SYMPATHETIC-STIMULATION

Appreciation has grown for the impact of the autonomic nervous system on the development of clinical cardiac arrhythmias. Antiarrythmic medi cations work to significantly prolong cardiac repolarization and slow conduction, The question has arisen whether these pharmacologic action s of antiarrhythmic drugs can be modulated by alterations in the sympa thetic nervous system, This article examines the data pertaining to mo dulation of the class I and class III effects of antiarrhythmic drugs during beta-adrenergic stimulation, the body's natural response stress . The actions of several antiarrhythmic con be fully reversed during b eta-adrenergic sympathetic stimulation. Overall, the data suggest that pure class III drugs are the most susceptible to reversal of their ef fects on refractoriness, followed by class IA agents, amiodarone (whic h has partial resistance), and d,l-sotalol (which is highly resistant to reversal). Whereas retrospective analyses of a number of trials sug gest that sympathetic-stimulation-induced reversal of the electrophysi ologic effects of certain antiarrhythmic drugs can decrease their clin ical efficacy, prospective trials examining this issue are needed. At the current time it appears reasonable to administer beta blockers to patients receiving antiarrhythmic agents that do not have intrinsic an tiadrenergic effects. (C)1998 by Excerpta Medica, Inc.