Automatic assessment of atrial pacing threshold in current medical practice

Introduction: Unlike ventricular level where automatic threshold measurement is validated by analyzing response to stimulation, automatic atrial threshold measurement is obtained by an individual approach based on the laws of cardiac electrophysiology.

Aim of this study is to validate the automatic atrial threshold monitoring algorithm by comparing measurements assessed by automatic system (ACM: atrial capture management) and by physician (MAT: manual atrial threshold) at patient discharge, 2 months and 8 months follow-up.

Method: Multi-centric prospective study of 352 patients (76.3±9.4 years old): 64% with atrio-ventricular block and 36% with sinus dysfunction, implanted with EnPulse® DR pacemakers. No specific programming was imposed. The automatic atrial threshold monitoring function was maintained at nominal programming after implant; daily of ACM was maintained at 1 hour in the night.

Results: Ambulatory ACM assessment was impossible for 30 patients at discharge (8.5%, but after only 3 days of monitoring): 14 patients due to atrial arrhythmias (AF) and 16 patients due to permanent atrial and ventricular pacing (AP-VP);

8 patients at 2 months (2.7%) and 11 patients at 8 months (4.3%). MAT was impossible for 0.3% of patients at discharge, 3.7% at 2 months and 5.9% at 8 months either for AF or AP-VP.

The difference of means between ACM and MAT is 0.009 Volts at discharge, 0.021 V at

2 months and 0.038 V at 8 months. The means of differences are 0.021 V at discharge, 0.044 V at 2 months and 0.043 V at 8 months.

There is excellent correlation between the two methods with a regression coefficient of 0.910 at discharge, 0.890 at 2 months and 0.916 at 8 months follow-up.

For 95.4% of patients at discharge, 92.9% at 2 months and 93% at 8 months, the difference between ACM and MAT was less or equal to 0.25 v. Difference was equal to 0.5 V for 1.9%, 2.2% and 1.7% of patients at discharge, 2 months and 8 months follow-up. A difference more than 0.5 V between the two methods was not observed.

Conclusion: Results of the study show excellent correlation in current medical practice between the two methods for atrial threshold: there is no statistical difference between ACM and MAT.