Worldwide clinical experience with a new dual-chamber implantable cardioverter defibrillator system

New Dual-Chamber ICD. Introduction: Management of atrial tachyarrhythmias r epresents a significant challenge in patients with implantable cardioverter defibrillators (ICDs). Drug therapy of these arrhythmias is limited by mod erate efficacy, ventricular proarrhythmia, and drug-device interactions. Th is study tested the safety and efficacy of a new dual-chamber ICD to detect and treat atrial as well as ventricular tachyarrhythmias, Methods and Results: A dual-chamber ICD (Medtronic 7250 Jewel AF) was impla nted in 293 of 303 patients at 49 centers in Europe, Canada, and North Amer ica. Specific data were collected at implant and during a mean follow-up pe riod of 7.9 +/- 4.7 months. There were no clinically evident failures to de tect and treat ventricular arrhythmias. In patients with at least one of th e dual-chamber detection criteria activated, 1,056 of 1,192 episodes of ven tricular tachycardia or fibrillation detected were judged to be appropriate (89 % positive predictive accuracy). Therapy efficacy was 100 % in the ven tricular fibrillation zone and 98 % in the ventricular tachycardia zone. Po sitive predictive accuracy for detection of atrial episodes was 95 % (1,052 /1,107), For episodes classified as atrial tachycardia by the device, the e fficacy of atrial antitachycardia pacing and high-frequency (50-Hz) burst p acing was 55% and 17%, respectively. High-frequency burst pacing terminated 16.8% of episodes classified as atrial fibrillation, and atrial defibrilla tion had an estimated efficacy of 76 %. The actuarial estimates of 6-month complication-free survival and total survival were 88 % and 94 %, respectiv ely. Conclusion: This novel dual-chamber ICD is capable of safely and effectivel y discriminating atrial from ventricular tachyarrhythmias and of treating a trial tachyarrhythmias without compromising detection and treatment of vent ricular tachyarrhythmias.