Abstract 8916: Frequency Analysis of the QRS Differentiates Left Bundle Branch Pacing from RV Septal Pacing

Abstract

Introduction: Left bundle branch pacing (LBBP) is an increasingly common procedure. The pacing lead is advanced via the RV septum into the myocardium with the goal of directly stimulating the LBB for more effective left ventricular (LV) activation. We have previously found that QRS frequency is useful for assessing successful LV activation in cardiac resynchronization therapy. Hypothesis: We surmised that the QRS complex of patients who underwent LBBP would exhibit significantly different frequency characteristics than simple RV septal pacing. Methods: We analyzed the QRS frequency of 36 patients with normal LV ejection fraction (≥50%) who have undergone LBBP for comparison to 33 patients who underwent RV septal pacing. Time frequency analysis was performed which yields a weighted average frequency (AKA: “center of energy” frequency or Cf) of the QRS. Chest lead V2 yielded the best frequency discrimination. We performed ROC analysis for all significant variables in multivariate analysis to obtain the area under the curve (AUC) predictive value. Results: See table: QRS duration, LVAT: paced LV activation time, AUC: area under the curve. Conclusions: Our data show that the QRS in LBB paced patients is significantly shorter and has a much higher Cf in lead V2 with high predictive value by ROC analysis compared to RV septal pacing. Baseline LVEF and paced LVAT exhibited lower AUC values. Such measurements may be of use during implantation of the pacing lead to ensure capture of the LBB when LV activation times and/or morphologic changes are equivocal.