Key result
When atrioventricular delay optimization was not possible, leadless biventricular left bundle pacing outperformed left bundle pacing alone by significantly shortening 90% biventricular activation times (54.2 vs 66.9 ms).
Why the study?
To quantify ventricular synchrony induced by leadless BIV-endo pacing and LBP, and investigate how RV-LV delay, RV lead location, and left bundle capture type affect response.
Does leadless biventricular pacing improve ventricular activation times compared to left bundle pacing alone in computational models of LBBB?
Does leadless biventricular pacing improve ventricular activation times compared to left bundle pacing alone in computational models of LBBB?
Absolute Event Rate: 54.2% vs 66.9%
p-value: p=<0.01
In computational models of LBBB, leadless biventricular pacing targeting the left bundle or LV lateral wall provides effective resynchronization, particularly when AV delay optimization is not possible.
Supports leadless biventricular pacing over LBBP alone without AV optimization in LBBB models; hypothesis-generating for clinical translation.
Biventricular endocardial (BIV-endo) pacing and left bundle pacing (LBP) are novel delivery methods for cardiac resynchronization therapy (CRT). Both pacing methods can be delivered through leadless pacing, to avoid risks associated with endocardial or transvenous leads. We used computational modelling to quantify synchrony induced by BIV-endo pacing and LBP through a leadless pacing system, and to investigate how the right-left ventricle (RV-LV) delay, RV lead location and type of left bundle capture affect response. We simulated ventricular activation on twenty-four four-chamber heart meshes inclusive of His-Purkinje networks with left bundle branch block (LBBB). Leadless biventricular (BIV) pacing was simulated by adding an RV apical stimulus and an LV lateral wall stimulus (BIV-endo lateral) or targeting the left bundle (BIV-LBP), with an RV-LV delay set to 5 ms. To test effect of prolonged RV-LV delays and RV pacing location, the RV-LV delay was increased to 35 ms and/or the RV stimulus was moved to the RV septum. BIV-endo lateral pacing was less sensitive to increased RV-LV delays, while RV septal pacing worsened response compared to RV apical pacing, especially for long RV-LV delays. To investigate how left bundle capture affects response, we computed 90% BIV activation times (BIVAT-90) during BIV-LBP with selective and non-selective capture, and left bundle branch area pacing (LBBAP), simulated by pacing 1 cm below the left bundle. Non-selective LBP was comparable to selective LBP. LBBAP was worse than selective LBP (BIVAT-90: 54.2 ± 5.7 ms vs. 62.7 ± 6.5, p < 0.01), but it still significantly reduced activation times from baseline. Finally, we compared leadless LBP with RV pacing against optimal LBP delivery through a standard lead system by simulating BIV-LBP and selective LBP alone with and without optimized atrioventricular delay (AVD). Although LBP alone with optimized AVD was better than BIV-LBP, when AVD optimization was not possible BIV-LBP outperformed LBP alone, because the RV pacing stimulus shortened RV activation (BIVAT-90: 54.2 ± 5.7 ms vs. 66.9 ± 5.1 ms, p < 0.01). BIV-endo lateral pacing or LBP delivered through a leadless system could potentially become an alternative to standard CRT. RV-LV delay, RV lead location and type of left bundle capture affect leadless pacing efficacy and should be considered in future trial designs.
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Strocchi et al. (2022) studied Left bundle branch block (n=24). Leadless biventricular left bundle pacing vs. Left bundle pacing alone was evaluated on 90% biventricular activation time (BIVAT-90) (p=<0.01). When atrioventricular delay optimization was not possible, leadless biventricular left bundle pacing outperformed left bundle pacing alone by significantly shortening 90% biventricular activation times (54.2 vs 66.9 ms).
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