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Continuous long-term monitoring of atrial fibrillation (AF) and tachycardia (AT) is an unmet clinical need, which could be met with a chronically-implanted monitor. Improved therapeutic decisions based on accurate monitoring of parameters, such as daily AF/AT burden (hours/ day) may lead to improvements in clinical outcomes such as reduction in hospitalizations, symptoms, and strokes. This paper describes an AF/AT detector that detects AF as well as AT with an irregular ventricular response, and a supplementary AT detector for AT with more regular ventricular response. Seven databases with significant durations of AF, AT, and sinus rhythm were used to evaluate the performance of the detectors. All patient records with AF (N = 124) were detected by the AF/AT detector to have AF/AT burden with a mean, median, and 75 percentile of absolute error in burden detection of 8.8, 0, and 4 min, respectively. In patients having AF burden (= or > 10 min), the AF/AT detector was found to have burden accuracy within 20% of true burden in 96% of patients. The specificity was 94%, defined as follows: in patient records without AF/AT (N = 174), the percentage with AF/AT burden = or < 10 min in the 24-h recordings. The AF/AT detector underestimatesAT burden, thus degrading performance, in patients with significant amounts of AT with more regular ventricular response. The supplementary AT detector reduces the underestimation of AT while overestimating burden in patients without a significant amount of AT. The detectors described here could be implemented in an implantable monitor for accurate long-term AF/AT monitoring.

We conclude that multisite right atrial pacing is feasible, effective and safe for long-term application. Atrial pacing significantly prolongs arrhythmia-free intervals in patients with drug-refractory paroxysmal AF. Dual-site right atrial pacing may offer additional benefits and should be considered either as the primary mode or in patients unresponsive to single-site pacing.

Background-Approximately 25% of patients who receive an implantable cardioverter-defibrillator (ICD) to treat ventricular tachyarrhythmias have documented atrial tachyarrhythmias before implantation. This study assessed the ability of device-based prevention and termination therapies to reduce the burden of spontaneous atrial tachyarrhythmias. Methods and Results-Patients with a standard indication for the implantation of an ICD and 2 episodes of atrial tachyarrhythmias in the preceding year received a dual-chamber ICD (Medtronic 7250 Jewel AF) that uses pacing and shock therapies for prevention and/or termination of atrial tachyarrhythmias. In a multicenter trial, patients were randomized to 3-month periods with atrial therapies "on" or "off" and subsequently crossed over. Analysis was performed on the 52 of 269 patients who had episodes of atrial tachyarrhythmia and had Ն30 days of follow-up with atrial therapies on and off. The atrial therapies resulted in a reduction of atrial tachyarrhythmia burden from a mean of 58.5 to 7.8 h/mo. A paired analysis (Wilcoxon signed-rank test) showed that the median difference in burden (1.1 h/mo) was highly significant (Pϭ0.007). When the subgroup of 41 patients treated only with atrial pacing therapies was analyzed, the reduction in burden persisted (Pϭ0.01). Conclusions-In this study, patients with a standard ICD indication and atrial tachyarrhythmias had a significant reduction in atrial tachyarrhythmia burden with use of atrial pacing and shock therapies.