Journal of Interventional Cardiac Electrophysiology 12, 149–156, 2005 C  2005 Springer Science + Business Media, Inc. Manufactured in The Netherlands. Implantable Dual-Chamber Defibrillator for the Selective Treatment of Spontaneous Atrial and Ventricular Arrhythmias: Arrhythmia Incidence and Device Performance Andreas Schuchert, 1 Giuseppe Boriani, 2 Christian Wollmann, 3 Mauro Biffi, 2 Martin K ¨ uhl, 4 Johannes Sperzel, 5 Sascha Stiller, 6 Gianni Gasparini, 7 and Dirk B ¨ ocker 3 1 University of Hamburg, Germany; 2 Institute of Cardiology, University of Bologna, Italy; 3 Department of Cardiology, University of M ¨ unster, Germany; 4 Guidant Europe, Belgium; 5 Bad Nauheim, Germany; 6 University of Ulm, Germany; 7 Mestre Hospital, Italy, on behalf of the VENTAK PRIZM AVT Investigators Abstract. Introduction: Atrial tachyarrhythmias are a common co-morbidity in patients with an ICD indica- tion. Recently introduced ICD’s are equipped to inde- pendently detect and treat atrial and ventricular tach- yarrhythmias. The purpose of this prospective study was to evaluate the incidence and termination of spon- taneous atrial and ventricular tachyarrythmias in pa- tients with a history of atrial tachyarrhythmias. Methods and Results: Ninety patients, 70% male with an ICD indication and history of atrial tachyarrhyth- mia (LVEF 45 ± 6%, [AT/AF indication 55 ± 10, AT/VT 45 ± 16], 46% CAD) were enrolled and 89 were im- planted with a VENTAK PRIZM AVT (Guidant). Spon- taneous atrial and ventricular tachyarrhythmias were printed and evaluated during an average follow-up pe- riod of 272 ± 72 days utilizing the stored intracardial electrogram function of the device. Nineteen patients (21%) presented had only atrial tachyarrhythmias, 32 patients (36%) had both atrial and ventricular tach- yarrhythmias and 18 patients (20%) had only ventric- ular tachyarrhythmias. Patients with only atrial tach- yarrhythmias had a total of 3274 atrial episodes; 2002 terminated spontaneously, 1264 were treated with ATP and 8 with shock therapy. ATP was successful in 735 (58%) of 1264 episodes. Patients with both atrial and ven- tricular tachyarrhythmias had 7277 documented atrial tachyarrhythmias, 5231 terminated spontaneously, 1153 of 2009 were terminated by ATP (57.4%) and 37 by shock therapy (20 patient controlled). Atrial tachyarrhyth- mias identified as atrial flutter (AT) by the atrial rhythm classification (ARC) algorithm had a higher ATP conver- sion success rate than episodes identified as atrial fib- rillation (AF); 66.7% for AT and 26.4% for AF. Patients with only ventricular tachyarrhythmias had 690 doc- umented episodes, 401 terminated spontaneously, 248 (85.8%) were terminated by ATP and 41 by shock. Conclusion: Seventy-seven percent of patients with an ICD indication had spontaneous atrial and/or ven- tricular tachyharrhythmias within the first 6 months after ICD implantation. ATP therapy terminated 58% of all atrial tachyarrhytmias and 66.7% of the atrial flut- ters. The dual chamber ICD detected, classified and ter- minated all ventricular tacharrhythmias appropriately. Key Words. spontaneous atrial and ventricular tachyarrhythmias, atrial fibrillation, atrial flutter, implantable cardioverter-defibrillator Introduction Atrial tachyarrhythmias are a frequent comor- bidity in patients with an indication for an im- plantable cardioverter defibrillator (ICD) that may be associated with increased morbidity, mor- tality and embolic events [1]. The use of devices with novel capabilities to detect and deliver multiple therapies for spon- taneous atrial and ventricular tachyarrhythmias has been recently proposed [2–4]. These devices may promptly restore sinus rhythm, which may be beneficial in selected patients with drug- refractory recurrent atrial fibrillation (AF), and in patients with both atrial and ventricular tach- yarrhythmias, in whom AF may facilitate the onset of ventricular tachyarrhythmias and/or in- appropriate shock therapy [4,5]. Therefore, in pa- tients who are candidates for a dual chamber ICD, it may be appropriate to implant a device Address for correspondence: Andreas Schuchert, MD, De- partment of Cardiology, University of Hamburg, Martinistr. 11, 20253 Hamburg, Germany. E-mail: Schuchert@uke.uni- hamburg.de Received 21 June 2004; accepted 3 November 2004 149