Abstract 18911: Ventriculo-Atrial (VA) Interval as a Measure of Proof of Capture of the Left Bundle

Abstract

Introduction: Left bundle branch area pacing (LBBAP) has provided a safe and effective method of capturing the conduction system for physiologic pacing. Given direct capture of the conduction system, we hypothesized that in patients with retrograde conduction, capture of the left bundle would result in shortening of the interval from ventricular activation to atrial activation (VA interval). To our knowledge, proof of shortening of the VA interval has only previously described as a diagnostic method of confirming left bundle capture in one published case report. In our proof-of-concept study we demonstrate VA interval shortening in 3 patients with intact retrograde conduction noted intraoperatively. Hypothesis: Capture of the left bundle will result in shortening of the VA interval and can be used as a method to confirm LBB capture in patients with intact retrograde conduction. Methods: VA interval measurements were made in patients with intact retrograde conduction. VA interval measurements were performed with capture of the RV septum only and with capture of the left bundle branch. Measurements were all made during implantation and occurred either during active lead deployment, or after left bundle branch area pacing results were obtained. If left bundle branch area pacing results were obtained first, then pacing unipolar from the ring was used as a surrogate for RV septal capture and pacing unipolar from the tip was used for left bundle capture.We did not distinguish between selective and non-selective left bundle branch pacing in this study. Results: In all three patients, capture of the left bundle resulted in shortening of the VA interval. Changes in VA interval were noted to be: 208 ms to 186 msec, 239 msec to 189 msec and 245 msec to 191 msec. The image in Figure 1 illustrates shortening of the VA interval. Conclusions: In patients with retrograde VA conduction, VA interval shortening may serve as an additional useful criterion of left bundle branch capture.