Antitachycardia pacing, therapy to treat spontaneous atrial tachyarrhythmias: the 7250 dual defibrillator Italian Registry

Background The dual defibrillator is a new device that can deliver atrial a ntitachycardia pacing (ATP) and shock therapies to treat atrial tachyarrhyt hmias in patients with and without life-threatening ventricular tachyarrhyt hmias. The aims of the present study were to investigate the efficacy of AT P and to identify factors that may impact on success of treatment. Method A total of 105 patients (80 male, mean age 64 +/- 10 years) implante d with a dual defibrillator were enrolled in the study;, 66% had documented atrial fibrillation (AF) before implantation and 14% had no history of pri or ventricular tachyarrhythmias. Results The follow-up lasted 6 +/- 5 months (range 1-24 months). A total of 863 treated atrial episodes were analyzed; 54.8% were classified as AF and 45.2% as atrial tachycardia (AT). The positive predictive value for atrial tachyarrhythmia was 97.7%. The efficacy of atrial ATP therapy was as follo ws: 48% overall, 70.9% on AT and 24.3% on AF. The overall efficacy of atria l shock was 100% for AT and 80% for AF. Atrial burst+ and ramp efficacy cor related well with atrial arrhythmia cycle length, whereas 50-Hz burst did n ot. As ATP delivery delay increased from 0 to 30 min, the mean atrial arrhy thmia cycle length shortened and ATP efficacy decreased. Class IC drug trea tment was associated with longer mean atrial cycles as compared with no the rapy or with class III drugs. Conclusion ATP therapies afforded by dual defibrillators were highly effect ive in treating spontaneous atrial tachyarrhythmias. Early treatment of suc h arrhythmias should improve success rates and patient benefits. (C) 2001 The European Society of Cardiology.