Electrophysiologic testing: predictive of amiodarone efficacy in recurrent sustained ventricular tachycardia?

The role of programmed ventricular stimulation (PVS) was evaluated in 12 patients with recurrent sustained ventricular tachycardia (VT) who were treated with amiodarone as the sole antiarrhythmic agent. At control PVS, sustained VT was induced in 11 patients and nonsustained VT was induced in one patient, as compared with late PVS (mean, 8.6 weeks) when sustained VT was induced in six patients and nonsustained VT was induced in five. Amiodarone significantly prolonged the patients' RR, PR, QRS, and QTc intervals, VT cycle length, and right ventricular effective refractory period. During a mean follow-up of 16 +/- 13.6 months, two patients had recurrent clinical VT. In the patients in whom amiodarone therapy failed (1) sustained VT was induced during late PVS, (2) VT cycle length and symptoms during late PVS and during recurrent clinical VT were similar, and (3) the QTc failed to be prolonged significantly (32.5 +/- 1.6 ms in amiodarone failure vs. 84.1 +/- 27.1 ms in amiodarone success, P<0.05). It is concluded that (1) amiodarone in high-risk patients is clinically effective (88.3%), (2) patients with noninducible VT or nonsustained VT during late PVS did not have recurrent clinical VT, (3) late PVS is probably predictive of electrophysiologic and hemodynamic consequences in patients with recurrent spontaneous VT, and (4) failure of the QTc interval to be prolonged substantially is probably predictive of clinical recurrence of VT.