Overdrive versus conventional or closed-loop rate modulation pacing in the prevention of atrial tachyarrhythmias in Brady-Tachy syndrome: on behalf of the Burden II Study Group.

BACKGROUND: Optimizing dual-chamber pacing to prevent recurrences of atrial tachyarrhythmias (AT) in sinus node dysfunction is still debated. Despite the large number of studies, efficacy of sophisticated preventive algorithms has never been proven. It is not clear whether this is due to imperfect study designs or to a substantial inefficacy of pacing therapies. AIM: To intraindividually compare AT burden between an atrial overdrive and two heart rate modulation approaches: a conventional accelerometric-sensor-based DDDR mode and a contractility-driven rate responsive closed loop (CLS) algorithm. METHODS AND RESULTS: Four hundred fifty-one patients with Brady-Tachy syndrome (BTS), severe bradycardia, and a documented episode of atrial fibrillation were enrolled. One month after implant, each pacing therapy was activated for 3 months in random order. A simple log transformation was used to handle large and skew AT burden distributions. Estimates were adjusted for false-positive AT episodes and reported as geometric means (95% confidence interval). A significantly higher AT burden was observed during overdrive, 0.14% (0.09%, 0.23%) (adjusted, 0.12%[0.07%, 0.20%]). Both DDDR and CLS performed better: respectively, 0.11% (0.07%, 0.17%) (adjusted, 0.08%[0.05%, 0.14%]), 0.06% (0.03%, 0.09%) (adjusted, 0.04%[0.03%, 0.07%]). All the comparisons were statistically significant. During overdrive significantly more patients had AT episodes of duration between 1 minute and 1 hour. No significant differences were observed for longer episodes. CONCLUSIONS: Atrial overdrive showed the worst performance in terms of AT burden reduction and should not be preferred to heart rate modulation approaches that still have to be considered as a first-choice pacing mode in BTS.

Role of ventricular Autocapture function in increasing longevity of DDDR pacemakers: a prospective study.

AIMS: Autocapture is an algorithm for automatic adaptation of ventricular output to capture threshold. The aim of this prospective study was to estimate the effects of ventricular Autocapture algorithm on DDD-DDDR pacemaker longevity. METHODS AND RESULTS: Eighty-three patients implanted with a DDD-DDDR pacemaker (Affinity or Entity; St Jude Medical, USA) were enrolled and the Autocapture function was activated pre-discharge. Ventricular pulse duration was randomly programmed at 0.3 or 0.4 ms, with a cross-over at 8-12 weeks and again at 13-14 months. Diagnostic data were retrieved from device memory and by calculating battery current drain from long-term threshold recordings; device longevity was estimated at the following settings: Autocapture with a pulse duration of 0.3 and 0.4 ms, respectively, standard output (3.5 V, 0.4 ms) and conventional low output programming (2.5 V, 0.4 ms). According to a series of assumptions, Autocapture was associated with a 55-60% increase in estimated device longevity compared with standard output programming and a 6-7% increase in longevity compared with low output programming. No significant differences were found between Autocapture programmed with a pulse duration of 0.3 or 0.4 ms. In projections to a 10-year follow-up, use of the Autocapture function resulted in a 42% reduction in pacing-related estimated costs compared with standard output programming at 3.5 V, 0.4 ms. CONCLUSION: Pacing with constant adaptation of ventricular output in dual-chamber devices has the potential to increase generator longevity and to reduce sizeably pacing-related costs compared with standard programming.