Assessment of long-term conduction system capture stability check using remote device electrograms in patients with permanent left bundle branch area pacing

In patients (pts) treated with Left Bundle Branch area Pacing (LBBaP), the evaluation of the long-term stability of conduction system capture (CSC) is essential because of the inherent risk of micro- or macro lead dislodgment, fibrosis, and changes in threshold capture value. Nowadays, 12-lead ECG recording at follow-up (FU) in the office represents the gold standard for confirming CSC.

We aimed to assess the feasibility of using device ventricular (V) EGM recordings at FU as a surrogate for standard 12-lead ECG to ensure long-term CSC and, therefore, stable true LBBaP.

A 12-lead ECG was performed after the LBBaP implant (BLP-ECG, baseline paced) and in-office 1-year after implant (Y1FU-ECG). Variations of Y1FU-ECG vs. BLP-ECG (QRS morphology/duration) were compared with the corresponding changes observed on remote V EGM recordings (Y1FU-EGM vs. BLP-EGM). At 12-leads ECG, we classified MACRO-change as a markedly wider (+30%) and notched-paced QRS duration (loss of CSC). MICRO-change shows a mild change in QRS duration and morphology (loss of typical r’ in V1). When reading the Near-Field on the V EGMs (NF-EGM), the following parameters were evaluated: a) time to peak (NF-TTP): time interval from the pacing artifact to the peak (pos or neg) of this sharp EGM deflection; b) morphology (NF-Morph): an initial sharp deflection - negative or positive - compared to the isoelectric line (associated to an increased NF-TTP).

Out of n=128 pts who underwent LBBaP for a permanent pacing indication at 4 sites (April 2023 to May 2024) and followed by remote monitoring, we analyzed n=48 pts who completed the 1-year FU. We found n=11 pts with Y1FU-ECG showing changes (3 pts with MACRO- and 8 pts with MICRO-changes) and n=37 pts with stable unchanged Y1FU-ECG. In the n=8 pts with ECG MICRO-changes, we observed an increased (>20ms) Y1FU-NF-TTP. In the 3 pts with ECG MACRO-changes, we observed a corresponding change in Y1FU-NF-Morph (reversal of initial sharp deflection) and an increased Y1FU-NF-TTP. In all the 37 pts with unchanged ECG, no changes were observed at Y1FU-NF-EGMs.

Table-1, Results

We could also observe "parallel" NF-EGM modifications at the intermediate EGM transmissions retrieved by remote monitoring systems in patients with long-term micro- or macro-ECG changes.

The analysis of V EGMs during remote monitoring transmissions could be instrumental in assessing the long-term CSC in patients treated with LBBaP. Compared with 12-leads ECG, the accuracy level should be prospectively investigated with a more extensive series of LBBaP pts.