Reproducibility of Electrophysiological Testing During Antiarrhythmic Therapy for Ventricular Arrhythmias Unrelated to Coronary Artery Disease

Although electrophysiological studies are commonly used in the management of patients with ventricular tachycardia (VT), the reproducibility of these studies during therapy has not been established in patients in whom VT is associated with conditions other than coronary artery disease. Therefore, we performed confirmation studies during drug therapy in 60 patients (mean age 48 +/- 18 years; 41 male) with sustained ventricular arrhythmias induced during initial study to assess the reproducibility of drug effect. The stimulation protocol used included the serial introduction of up to three premature ventricular stimuli during sinus rhythm and with ventricular pacing at two pacing rates. Rapid ventricular pacing techniques were also used. Antiarrhythmic drug efficacy was confirmed in 78% of patients. Sustained VT was induced at repeat electrophysiological study in 18% of patients during antiarrhythmic therapy that had been felt to be effective on the basis of a single drug study. We conclude that electrophysiological study results during antiarrhythmic therapy exhibit significant day-to-day variability. Sustained VT can be induced during antiarrhythmic therapy previously determined to be effective by electrophysiological techniques in many patients.