Early postoperative electrocardiographic changes after left bundle branch area pacing

During left bundle area pacing (LBBAP), careful attention is given to lead positioning and the electrocardiographic features of the stimulated QRS complexes. Little is known about the early perioperative electrocardiographic changes.

To investigate electrocardiographic differences between the surface 12-lead ECG at the time of implantation and on the first postoperative day.

We retrospectively analysed ECG tracings from 55 consecutive patients who underwent successful LBBAP implantation between May and October 2024 at our tertiary institution. During implantation and on the first operative day, we used 12-lead ECGs recorded during bipolar pacing at a sweep speed of 100mm/s. For each ECG, we measured QRS duration, frontal axis, R wave peak time in lead V6 (V6RWPT), and the presence of R’ in V1.

Overall, median age was 75 (IQR 63-87) years, and 9 (16%) patients were female. Compared to implantation, the QRS duration on the ECG at the first postoperative day was longer (119.27 vs. 125.18 ms, p=0.022). QRS axis showed a clockwise change with reduction in the angle from lead I (-34 vs. -10°, p=0.001). V6RWPT did not show any significant change (60.55 vs. 58.98 ms, p=0.465). We found that R’ in V1 was less prevalent on the first postoperative day compared to implantation (61% vs. 91%, p=0.0002).

12-lead ECGs on the first day after implantation of LBBAP showed significant changes in QRS duration, axis and presence of R’ in V1. These changes may be explained by different anodal capture between the two timepoints, microdislocation or resolution of tissue injury. Whether these changes translate into a different long-term outcomes warrants further studies.