[Usefulness of an electrophysiological study in the management of patients with tachyarrhythmias].

Supraventricular tachycardia or ventricular tachycardia can be induced by programmed electrical stimulation (PES) of the heart in patients who have the substrate for it. In supraventricular tachycardia, the nature of the substrate, which itself can identify the drug to be used to prevent tachycardia, can be determined by PES. However, the nature of the substrate for ventricular tachycardia may not be clarified by PES. Therefore, PES must be performed repeatedly until the drug which prevents the induction of tachycardia can be selected. Whether the therapy for preventing ventricular tachycardia can be selected by Holter monitoring or PES is controversial. Holter monitoring can select a drug which can suppress ventricular extrasystoles and thus reduce the likelihood of recurrent ventricular tachycardia, and PES can select a drug which can modify the underlying susceptibility of the heart to tachycardia. Reported studies have demonstrated that, as compared with PES criteria, Holter monitoring criteria more often indicate efficacy. Thus, when a drug is effective by PES criteria, it is usually effective by Holter monitoring criteria, and therapy selected by PES prevents recurrence of ventricular tachycardia better than does that selected by Holter monitoring. Efficacy according to PES predicts a good outcome, but many patients without efficacy according to PES do not have recurrences. Inefficacy by Holter monitoring predicts a poor outcome but efficacy by it does not necessarily prognosticate a good outcome. It is concluded that, in addition to the Holter monitoring method, PES can be valuable in selecting therapy and predicting the prognosis of patients.