Electrocardiographic repolarization changes following conduction system pacing in pacemaker-induced cardiomyopathy.

BACKGROUND

Pacemaker-induced cardiomyopathy (PICM) occurs in a subset of patients exposed to chronic right ventricular pacing (RVP) and results in left ventricular dysfunction due to pacing-related dyssynchrony. Left bundle branch area pacing (LBBAP) has emerged as a physiologic pacing strategy capable of restoring conduction system activation and reversing PICM. However, the acute effects of LBBAP on ventricular repolarization in PICM remain unclear. This study evaluated immediate repolarization changes after LBBAP in PICM compared with a control cohort of non-ischemic dilated cardiomyopathy (DCM) patients undergoing LBBAP.

METHODS

We retrospectively analyzed clinical, electrocardiographic, and pacing data from patients receiving successful LBBAP. Baseline and post-implant ECG intervals (QT, QTc, Tp-Te) were manually measured; T-wave memory (TWM) was qualitatively assessed. Procedure parameters (RWPT, V6-V1 interpeak interval, output-dependent QRS transition), procedural success, and complications were recorded.

RESULTS

Sixty patients were included (28 PICM vs. 32 DCM). Baseline LVEF was higher in patients with PICM compared to DCM (35 ± 8% vs. 29 ± 7%; p = 0.003). LBBAP success was similar (93% vs. 96%). PICM patients had wider paced QRS (149 ms vs. 128 ms; p = 0.02) and longer V6-V1 interval (46 ± 12 vs. 38 ± 10 ms; p = 0.02), but repolarization metrics showed no adverse changes and remained comparable between groups. QT shortened similarly (PICM: 476 → 437 ms; DCM: 466 → 432 ms), QTc minimally increased without group interaction, Tp-Te decreased, and TWM was frequent in both cohorts (63% vs. 64%). Complications rate was also comparable.

CONCLUSION

LBBAP does not induce unfavorable acute repolarization changes in PICM and yields repolarization responses comparable to DCM controls, supporting its safety and physiologic benefit in PICM upgrades.