Serial evaluation of atrial tachyarrhythmia burden and frequency after implantation of a dual-chamber cardioverter-defibrillator

Background: We sought to characterize atrial tachyarrhythmia (AT) burden and frequency after implantation of a dual-chamber implantable cardioverter-defibrillator (D-ICD). Methods and Results: A total of 149 subjects underwent implantation of a D-ICD (Jewel AF((R)) model 7250, Medtronic, Inc.) for the primary indication of drug-resistant AT, and were followed for at least 12 months during which device programming was constant. The device employed atrial overdrive pacing as well as shocks to terminate episodes of AT. Arrhythmia burden and frequency were evaluated during the 0- to 6-month follow-up and and 6- to 12-month follow-up intervals. A majority of subjects (62%) received a type I/III antiarrhythmic drug during follow-up. The median arrhythmia burden decreased from 8.2 hours/month during 0-6 months to 3.3 hours/month during 6-12 months (P = 0.004); this result was driven primarily by the subgroup with persistent AT prior to device implantation. There was no significant change in the median AT frequency (2.2 vs 1.0 episodes/month). There was a significant decrease in the median shock frequency (0.32 vs 0.00 shocks/month, P = 0.003) and an increase in shock efficacy (85.5% vs 94.9%, P = 0.01). Conclusions: Device-based treatment of AT, in association with antiarrhythmic drugs, yields a significant time-dependent decrease in AT burden but not frequency.