Antiarrhythmic drug therapy in the management of cardiac arrest survivors.

Antiarrhythmic drugs may be used as primary therapy to prevent recurrent cardiac arrest or as adjunctive treatment in patients given an implantable cardioverter defibrillator. In the latter instance, drugs are given to suppress nonlethal arrhythmias that are capable of initiating defibrillator discharge or to slow and/or decrease the number of episodes of sustained ventricular tachyarrhythmias. When used as primary therapy, drug efficacy should be judged by nonempirical methods, preferably serial electrophysiological testing. Although no study has compared noninvasive with invasive testing to determine antiarrhythmic drug effectiveness in a substantial number of cardiac arrest survivors, several investigations have demonstrated that electrophysiological testing is useful for this purpose. One important limitation of serial electrophysiological testing is that nearly 40% of cardiac arrest survivors do not have a sustained ventricular tachyarrhythmia initiated at baseline study; nonpharmacological treatment would appear preferable in these patients. Further, since a relatively high arrhythmic recurrence rate has been noted in individuals with suppressible sustained ventricular tachycardia/fibrillation during drug therapy and a left ventricular ejection fraction less than 30%, we recommend serial electrophysiological/pharmacological testing primarily for patients with inducible sustained ventricular tachyarrhythmias with an ejection fraction greater than or equal to 30%.