Tailoring the Atrioventricular Interval During Left Bundle Branch Pacing: Playing With Fusion.

BACKGROUND: Optimization of biventricular pacing for cardiac resynchronization therapy (CRT) with fusion (fusion-optimized intervals method) has been shown to improve left ventricular remodeling. However, information on programming the atrioventricular (AV) interval during left bundle branch pacing (LBBP) is scarce. OBJECTIVE: Assess with electrocardiographic imaging (ECGI) the electrical benefit of optimization of the AV interval during LBBP. METHODS: Retrospective analysis of prospectively collected data. Pilot study including patients who received LBBP with CRT indication, normal AV conduction, sinus rhythm, and left bundle branch block. ECGI was used to obtain non-invasive activation maps, ventricular activation times, and QRS widths during the optimization of the AV interval. RESULTS: A total of 10 patients who received LBBP were included. Median age was 62 years (57-74 years), 40% were women, 20% had ischemic cardiomyopathy, and baseline LVEF was 29% (23%-36%). The baseline median QRS duration was 178 ms (168-187 ms), with a left ventricular activation time (LVAT) of 99 ms (90-109 ms), a right ventricular activation time (RVAT) of 42 ms (34-71 ms), and a total ventricular activation time (TAT) of 111 ms (105-131 ms). A non-tailored AV programming showed a QRS measured from intrinsic deflection of 142 ms (137-149 ms); when a tailored AV was programmed, the median QRS decreased to 124 ms (116-130 ms). Ventricular activation times showed shortening with a tailored approach. CONCLUSION: AV interval adjustment during left bundle branch pacing may result in better resynchronization.