Impact of automatic adjustment of stimulation outputs on pacemaker longevity in a new dual-chamber pacing system.

Introduction: Automatic capture verification using the Autocapture (AC) feature enabled by paced evoked response detection and delivery of high energy back-up pulses intends to increase patient safety. Furthermore, adjustment of stimulation outputs can save energy and potentially improve pacemaker (PM) longevity. The purpose of this study was to evaluate the theoretical longevity of a new dual chamber PM with the integrated AC feature (Affinity DR, St. Jude Medical) in comparison to the longevity of a previous model from the same manufacturer without AC (Trilogy DR).

Method: Affinity PMs were implanted in 16 patients and connected to a compatible lead with low polarization properties. AC was activated when the evoked response was significantly higher than the polarization voltage. Theoretical PM longevity was calculated with and without AC during follow-up. The measured and calculated values were compared to measurements in 19 patients, who consecutively received Trilogy-PMs during the same time period.

Results: In only one patient the evoked response was not adequate, and as a result, AC was not programmed. The calculated longevity of the Affinity-PMs 79 +/- 28 days after implantation was significantly higher in comparison to the Trilogy-PMs (Affinity-PMs: 8.9 +/- 1.2 years without and 9.5 +/- 1.1 years with AC; Trilogy-PMs: 6.5 +/- 0.8 years) (p < 0.005).

Conclusion: The AC feature is an optional algorithm that can be activated in most patients and it significantly prolongs predicted battery longevity due to automatic adjustment of stimulation outputs.