ELECTROPHYSIOLOGICAL FINDINGS IN IDIOPATHIC RECURRENT VENTRICULAR-FIBRILLATION - SPECIAL REFERENCE TO MODE OF INDUCTION, DRUG-TESTING, AND LONG-TERM OUTCOMES

Electrophysiological studies can be useful in the presence of idiopath ic ventricular fibrillation (VF) and may be used when selecting antiar rhythmic drugs. However, the yield, the mode, and the long-term reprod ucibility of the induction of VF have not yet been fully elucidated. E ight patients with idiopathic VF underwent electrophysiological study. The mean age (+/- SD) was 45 +/- 17 years. Six were males and two wer e females. Diagnosis was done by exclusion. VF was induced in 6 (75%) of 8 patients using double extra stimuli at coupling intervals of 233 +/- 39 and 191 +/- 20 ms for the first and second extra stimuli, respe ctively. Of note, VF was induced by stimulation exclusively at the ori gin of the premature Ventricular beat, which was the first complex of VF in two patients. In another patient, VF was initiated by two premat ure stimuli and also by a pause produced by rapid pacing. The inducibi lity of VF was reproduced 9-18 months after the first induction in all of the four patients studied. When the ability of antiarrhythmic drug s to suppress VF inducibility was confirmed, no recurrence was observe d during the follow-up period of 40-160 months, bur a recurrence of VF was observed in one of two nonresponders. In one patient, amiodarone administration failed in preventing VF induction 9 months after initia tion of therapy, and reassessment of long-term drug-efficacy might be indicated in some patients. In conclusion, idiopathic VF was highly in ducible (75%) with double extra stimuli. In this study, it was induced from a specific site (2/8) or by a pause (1/8). Induction of VF seeme d to be reproduced 9-18 months after the first study. The outcome was considered favorable when the inducibility of VF was suppressed by ant iarrhythmic drugs.