Automatic management of atrial and ventricular stimulation in a contemporary unselected population of pacemaker recipients: the ESSENTIAL Registry.

AIMS: We investigated the applicability of the Ventricular Capture Control (VCC) and Atrial Capture Control (ACC) algorithms for automatic management of cardiac stimulation featured by Biotronik pacemakers in a broad, unselected population of pacemaker recipients. METHODS AND RESULTS: Ventricular Capture Control and Atrial Capture Control were programmed to work at a maximum adapted output voltage as 4.8 V in consecutive recipients of Biotronik pacemakers. Ambulatory threshold measurements were made 1 and 12 months after pacemaker implant/replacement in all possible pacing/sensing configurations, and were compared with manual measurements. Among 542 patients aged 80 (73-85) years, 382 had a pacemaker implant and 160 a pacemaker replacement. Ventricular Capture Control could work at long term in 97% of patients irrespectively of pacing indication, lead type, and lead service life, performance being superior with discordant pacing/sensing configurations. Atrial Capture Control could work in 93% of patients at 4.8 V maximum adapted voltage and at any pulse width, regardless of pacing indication, lead type, and service life. At 12-month follow-up, a ventricular threshold increase ≥1.5 V had occurred in 4.4% of patients uneventfully owing to VCC functioning. Projected pacemaker longevity at 1 month was strongly correlated with the 12-month estimate, and exceeded 13 years in >60% of patients. CONCLUSION: These algorithms for automatic management of pacing output ensure patient safety in the event of a huge increase of pacing threshold, while enabling maximization of battery longevity. Their applicability is quite broad in an unselected pacemaker population irrespectively of lead choice and service of life.

Atrial threshold variability: implications for automatic atrial stimulation algorithms.

BACKGROUND: Automatic management of atrial stimulation by verification of atrial threshold (ACM) has recently been made feasible. We investigated circadian atrial threshold variability over the long term and the predictors of successful automatic atrial threshold measurement, in order to provide practical clues for programming ACM features, in such a way as to achieve daily threshold verification and > 99% effective atrial stimulation. METHODS: Six daily attempts to measure atrial threshold were programmed in patients receiving an EnPulse pacemaker (Medtronic Inc., Minneapolis, MN, USA). Atrioventricular (AV) conduction was maximized by programming Search AV+ (SAV+) to a resting Paced AV delay = 400 ms in the first month, and 600 ms thereafter. RESULTS: Seventy-six patients had a median follow-up of 12 months. Median ACM success was 77%. Concordance between automatically and manually measured thresholds was observed during the entire follow-up (Rho = 0.82, P < 0.001). Daily variability in atrial threshold was < 0.5 V in > 94% of measurements in the first trimester after implantation, and < 0.5 V in > 99% of measurements thereafter, as well as any time after pacemaker replacement. Atrial threshold was measured on 86% of days: the predictors of ACM failure were AV block (AVB), high%Atrial pacing, and atrial fibrillation. Programming SAV+ to achieve 600 ms resting Paced AV decreased%Vpacing in patients with normal AV conduction and first-degree AVB, improving the ability to detect atrial threshold. CONCLUSIONS: The reliability of ACM is high over a long follow-up. On the basis of atrial threshold variability, a practical approach to ACM programming should be two daily atrial threshold measurements in patients with normal AV conduction and%Ap < or = 40%, or with normal sinus activity and AVB, whereas 3-4 measurements should be recommended in patients with first-degree AVB and%Ap > 40% or with recurrent atrial fibrillation and AVB. The lowest adapted stimulation output should achieve at least threshold +1 V in the first trimester after implantation, then threshold +0.5 V thereafter, in order to achieve > 99.5% effective atrial stimulation.