Optimal pace timing for left bundle branch area pacing with or without an additional LV lead: results from the CSPOT study.

AIMS: This study aimed to determine optimal atrioventricular (AV) timing for left bundle branch area pacing (LBBAP) and optimal AV and interventricular (VV) timing for LBBAP optimized cardiac resynchronization therapy (LOT-CRT) to enhance the benefit of conduction system pacing.

METHODS AND

RESULTS

Acute measurements of LV dP/dtmax and QRS duration were collected during sweeps of AV and VV delays during paired comparison of LBBAP, LOT-CRT, and biventricular pacing (BVP) in 48 CRT-indicated patients. Optimal AV delays were selected as the vertex of a parabolic model fit to the AV sweep results, obtained independently for LV dP/dtmax and QRS duration. LBBAP, LOT-CRT, and BVP were similarly sensitive to the choice of AV delay, and 60 ms deviations from optimal AV delay resulted in an approximately 30% reduction in the haemodynamic benefits of resynchronization. Based upon LV dP/dtmax measurements, the average optimal paced AV (PAV) for LBBAP (152 ms) was significantly shorter than that for LOT-CRT (171 ms, P < 0.01) or BVP (167 ms, P = 0.01). Based upon QRS duration, the average optimal PAV for LBBAP (164 ms) was similar to that for LOT-CRT (160 ms, P = 0.52) or BVP (165 ms, P = 0.95). For each resynchronization modality, a linear regression between the patient's measured intrinsic AV conduction and their optimal AV delay provided a patient-specific AV delay, resulting in improved AV selection compared to applying a fixed AV delay to all patients. Finally, simultaneous activation (VV = 0) was best for both LOT-CRT and BVP.

CONCLUSION

LBBAP, LOT-CRT, and BVP are similarly sensitive to AV-timing. Optimal AV delay is linearly related to intrinsic AV for each resynchronization modality. For LOT-CRT and BVP, simultaneous biventricular activation is best on average.

CLINICAL TRIAL REGISTRATION INFORMATION: https://clinicaltrials.gov/study/NCT04905290.