Prevention of sustained ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillators-the PREVENT study.

Background: In patients with implantable cardioverter-defibrillators (ICDs), 25 to 45% of tachyarrhythmia episodes were initiated by short-long-short RR intervals.

Methods: The prospective multi-center PREVENT study randomized patients implanted with ICDs capable of atrioventricular pacing, in order to compare-using a cross-over design with two 3-month treatment periods-the benefits of 'rate smoothing' (RS) as a 'pause-prevention algorithm' for the prevention of ventricular tachyarrhythmias.

Result: Follow-up included 219 patients with implanted ICDs, of whom 153 were eligible for analysis as per protocol. Fifty-seven of these patients (38%) had documented episodes of ventricular tachyarrhythmias during the six months follow-up. The total number of sustained ventricular tachyarrhythmia episodes was reduced from 358 with RS Off to 145 with RS On. RS was effective in reducing the number of short-long-short induced sustained ventricular episodes from 100 with RS Off to 40 with RS On. The Wilcoxon-Mann-Whitney point estimator equals 0.66 with a 95% confidence interval from 0.51 to 0.82 (relevant superiority; corresponding p = 0.039). There were no proarrhythmic effects due to rate smoothing within the scope of this study.

Conclusions: 'Rate smoothing' significantly reduced sustained ventricular tachyarrhythmias in ICD patients. There is a relevant superiority of the treatment during the early six months of follow-up.