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 antitachycardia pacing (ATP) and shock therapies to treat atrial tachyarrhythmias in patients with and without life-threatening ventricular tachyarrhythmias. The aims of the present study were to investigate the efficacy of ATP and to identify factors that may impact on success of treatment. Method A total of 105 patients (80 male, mean age 64 +/- 10 years) implanted with a dual defibrillator were enrolled in the study;, 66% had documented atrial fibrillation (AF) before implantation and 14% had no history of prior 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 follows: 48% overall, 70.9% on AT and 24.3% on AF. The overall efficacy of atrial shock was 100% for AT and 80% for AF. Atrial burst+ and ramp efficacy correlated well with atrial arrhythmia cycle length, whereas 50-Hz burst did not. As ATP delivery delay increased from 0 to 30 min, the mean atrial arrhythmia cycle length shortened and ATP efficacy decreased. Class IC drug treatment was associated with longer mean atrial cycles as compared with no therapy or with class III drugs. Conclusion ATP therapies afforded by dual defibrillators were highly effective in treating spontaneous atrial tachyarrhythmias. Early treatment of such arrhythmias should improve success rates and patient benefits. (C) 2001 The European Society of Cardiology.