Atrial Threshold Variability: Implications for Automatic Atrial Stimulation Algorithms

Abstract

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.

Performance Evaluation of a Right Atrial Automatic Capture Verification Algorithm using Two Different Sensing Configurations

“…Their results also suggest limited algorithm performance in patients with intermittent AF, rate variability, and significant pacemaker dependence 43 . These results were confirmed by Biffi et al, who reported success rates for the conduction‐based algorithm of 27% in first‐degree and 0% in second‐ and third‐degree AV blocks 42 . Biffi et al also reported success rates below 50% and 30% for patients who had 50% and nearly 100% atrial pacing, respectively.…”

“…Although the ER‐based ACV algorithm evaluated in this study may be limited to leads with two or more electrodes, this study suggests that such a barrier can be overcome by appropriate safety‐margin programming in accordance with previously suggested programming levels. In an attempt to provide ACV in all lead designs, others have evaluated a conduction‐based algorithm, relying on stable sinus rhythm or stable AV conduction, as an alternative for automatic atrial threshold measurement 42,43 . In one study, the conduction‐based algorithm reported an inability to measure atrial threshold in 30.7% of attempts 43 ; similarly, in another study, atrial threshold measurements were successfully obtained in only 65% of attempts 42 .…”

“…In an attempt to provide ACV in all lead designs, others have evaluated a conduction‐based algorithm, relying on stable sinus rhythm or stable AV conduction, as an alternative for automatic atrial threshold measurement 42,43 . In one study, the conduction‐based algorithm reported an inability to measure atrial threshold in 30.7% of attempts 43 ; similarly, in another study, atrial threshold measurements were successfully obtained in only 65% of attempts 42 . In comparison, our results showed that the ER‐based ACV algorithm successfully obtained atrial threshold measurements in more than 90% of attempts, using a narrower margin of error than the studies evaluating the conduction‐based algorithm (i.e., ± 0.2 V vs ± 0.25 V 42 or −0.25 V, + 0.5 V 43 ).…”

Manual vs. automatic capture management in implantable cardioverter defibrillators and cardiac resynchronization therapy defibrillators

“…7,10 Manual thresholds are performed using 0.25 V threshold steps, whereas the automatic thresholds use 0.125 V steps. When all other variables are equal, this difference in step size will result in manually measured thresholds that are on average slightly larger than automatically measured thresholds.…”

“…The 3-month follow-up was chosen for analysis because the maximum number of patients had device data for this period. Although CM applicability may be higher with more frequent measurement attempts, 10 a daily measurement was chosen as a trade-off between achieving the highest applicability without excessive measurement attempts. The CM applicability was determined for the following periods: 1, 3 days, 1 week, 1, and 3 months prior to the 3-month follow-up.…”