Use of an Atrial Lead with Very Short Tip-To-Ring Spacing Avoids Oversensing of Far-Field R-Wave

The AVOID-FFS (Avoidance of Far-Field R-wave Sensing) study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS) when compared to a conventional atrial lead in combination with optimization of the programming.Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB) was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation.A total of 204 patients (121 male; age 73±10 years) were included in the study. False positive mode switch caused by FFS was detected in one (1%) patient of the study group and two (2%) patients of the control group (p = 0.62).The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization.ClinicalTrials.gov NCT00512915

Study flow-chart.

<p>Study flow-chart.</p

Inappropriate mode switch due to FFS: Stored episode depicting inappropriate mode switch due to FFS from the control group.

<p>Despite optimized PVAB of 140 ms inappropriate mode switch occurs because the coupling interval of the far-field R-wave is 160 ms. First line: bipolar atrial electrogram, shows bipolar atrial, second line: bipolar ventricular electrogram, bottom line: marker channel with AMS = mode switch; AP = atrial pacing; AS = atrial sensed event; AS on black background = atrial sensed event in refractory period; VP = ventricular pacing.</p

Electrical parameters of the atrial leads.

<p>Electrical parameters of the atrial leads.</p

Distribution of programmed PVAB during follow-up by randomization groups.

<p>Nine patients of the study group initially received a PVAB that was erroneously programmed to a value other than 60 ms which was corrected after one month in eight of the patients and remained prolonged in one patient. None of these patients had inappropriate mode switch due to FFS. One patient of the study group patient exhibited inappropriate mode switch due to FFS and the PVAB was then individually optimized (150 ms). For the control group PVAB is shown as determined to be optimal at discharge. In case of changes of the PVAB programming during the follow-up, the longest programmed PVAB for both groups are displayed.</p

Baseline characteristics of the patients.

*<p>According to the implanter’s judgment.</p