Early intraoperative risk stratification of persistent high pacing threshold after atrial septal pacing with a...

Atrial septal pacing with the 3830 lead is increasingly used, but some patients show high pacing thresholds (PT) immediately after fixation, and elevated thresholds may persist. Practical criteria based on early intraoperative findings for identifying such cases have not been established.

We retrospectively studied 53 consecutive patients who underwent cardiac implantable electronic device implantation with the 3830 lead positioned in the high right atrial septum. PT, sensing amplitude, impedance, and current of injury (COI) were measured immediately after fixation, at 5 and 10 min after fixation, post-procedure, at 1 week, and 3 months. The initial high-threshold group was defined as PT ≥ 1.5 V/0.4 ms immediately after fixation. In this group, we evaluated a two-step strategy using PT and COI at 5 min. The primary outcome was PT > 1.0 V/0.4 ms at 1 week.

Of 53 patients, 26 were classified into the initial high-threshold group. In this group, PT improved from 2.000[1.750-2.438] V immediately after fixation to 0.750[0.500-0.875] V at 1 week (p < 0.001). Three patients (11.5%) met the primary outcome. PT ≥ 2.5 V/0.4 ms at 5 min yielded 100.0% sensitivity, 95.7% specificity, 75.0% positive predictive value, and 100.0% negative predictive value. In this cohort, adding a 5-min COI cutoff ≤ 2.1 mV to 5-min PT yielded 100.0% for all diagnostic metrics in this cohort.

In this pilot study, most cases with high PT immediately after fixation improved within 1 week. A two-step assessment using PT and COI at 5 min after fixation may provide an exploratory framework for intraoperatively stratifying cases at risk of persistent high threshold at 1 week.