[Factors predicting the response to an antiarrhythmic during an electrophysiologic study for ventricular tachycardia]

The purpose of this study was to search for factors correlated with the absence of reinduction of a clinical ventricular tachycardia (VT) by stimulation in patients under anti-arrhythmic treatment. Repeated stimulations were performed in 41 patients with spontaneous VT and sustained, monomorphous ventricular arrhythmia induced by stimulation. The stimulation included 1 or 2 extrastimuli delivered into the right ventricle in sinus rhythm, then in imposed ventricular rhythm (600-400 ms). At least 4 anti-arrhythmic drugs were tested. In 16 patients (group I) of mean age 51 +/- 11 years VT was no longer reinducible under anti-arrhythmic treatment. In 25 patients (group II) of mean age 57 +/- 12 years no anti-arrhythmic drug was able to prevent VT induction. The characteristics of spontaneous and induced VT and of isotopic left ventricular ejection fraction (LVEF) were compared in both groups. The absence of reinduction of VT was obtained more easily in patients with: spontaneous, frequently unsustained VT; VT requiring 2 ventricular extrastimuli delivered in imposed rhythm to be induced; rapid initial induced VT (cycle 233 +/- ms vs 297 +/- 63 ms); less advanced underlying heart disease (LVEF 38 +/- 18 vs 27 +/- 13%). The subsequent history of the patients showed that the absence of reinduction of VT was correlated with a low risk of recurrence of VT (12.5 vs 48%) and with a lower risk of mortality (6% vs 32%) than in patients whose VT was always inducible under anti-arrhythmic treatment.