Correlations between myocardial injury current and lead performance in His bundle pacing compared with left bundle branch area pacing and right ventricular septum pacing.

Background: Conduction system pacing by implanting the lead in the His bundle (HBP) region or in the left bundle branch area (LBBAP) has gained popularity. Myocardial injury current (IC) is useful for predicting adequate lead fixation in right ventricular septal pacing (RVSP).

Objectives And Methods: We compared the correlations between IC and lead performance among patients receiving HBP (n = 41), LBBAP (n = 53), and historical RVSP (n = 88). LBBAP was an alternative if optimal HBP was not achieved. A positive IC (ST - ST) was defined as > 0.2 mV or a > 25% ST elevation and prolongation of the ventricular electrograms > 10 ms from baseline.

Results: HBP patients with a positive IC (48%, 0.84 ± 0.4 V/0.4 ms) exhibited a similar pacing threshold to their LBBAP counterparts (76%, 0.75 ± 0.3 V/0.4 ms, p = 0.329), but a higher pacing threshold than their RVSP counterparts (67%, 0.50 ± 0.1 V/0.4 ms, p < 0.001) at implantation. The R-wave (5.70 ± 3.4 mV) and impedance (660.91 ± 140.8 Ω) were both lower than those of LBBAP (10.35 ± 6.0 mV, p = 0.002; 822.36 ± 235.8 Ω, p = 0.005) and RVSP (11.24 ± 4.9 mV, p < 0.001; 754.27 ± 126.4 Ω, p = 0.006) patients respectively at implantation. The trend of electrical parameter comparisons remained unchanged during follow-up (3.56 ± 1.4 months). Notably, HBP patients without ICs had a higher pacing threshold (1.24 ± 0.6 V/0.4 ms) compared to their LBBAP (0.73 ± 0.3 V/0.4 ms, p = 0.009) and RVSP (0.53 ± 0.1 V/0.4 ms, p < 0.001) counterparts at implantation and during follow-up.

Conclusions: The detection of positive changes of myocardial ICs during HBP was associated with a better capture threshold equivalent to the LBBAP counterpart both at implantation and during short-term follow-up. Further large-scale studies with longer follow-up are necessary to confirm these findings.