Bipolar anodal septal pacing with direct LBB capture preserves physiological ventricular activation better than unipolar left bundle branch pacing

Abstract

Background: Left bundle branch pacing (LBBP) produces delayed, unphysiological activation of the right ventricle. Using ultra-high-frequency electrocardiography (UHF-ECG), we explored how bipolar anodal septal pacing with direct LBB capture (aLBBP) affects the resultant ventricular depolarization pattern. Methods: In patients with bradycardia, His bundle pacing (HBP), unipolar nonselective LBBP (nsLBBP), aLBBP, and right ventricular septal pacing (RVSP) were performed. Timing of local ventricular activation, in leads V1-V8, was displayed using UHF-ECG, and electrical dyssynchrony (e-DYS) was calculated as the difference between the first and last activation. Durations of local depolarizations were determined as the width of the UHF-QRS complex at 50% of its amplitude. Results: aLBBP was feasible in 63 of 75 consecutive patients with successful nsLBBP. aLBBP significantly improved interventricular dyssynchrony (-9 ms (-12;-6) vs. -24 ms (-27;-21), ), p < 0.001) and shortened local depolarization durations in V1-V4 (mean differences -7 ms to -5 ms (-11;-1), p < 0.05) compared to nsLBBP. Both aLBBP and HBP caused similar absolute levels of interventricular dyssynchrony (e-DYS -9 ms (-12; -6) vs. 10 ms (7;14); however, local depolarization durations in V1-V2 during aLBBP were longer than HBP (differences 5-9 ms (1;14), p < 0.05, with local depolarization duration in V1 during aLBBP being the same as during RVSP (difference 2 ms (-2;6), p = 0.52). Conclusion: Although aLBBP significantly improved interventricular synchrony and depolarization duration of the septum and RV compared to unipolar nsLBBP, the resultant ventricular depolarization was still less physiological than during HBP.

Ventricular dyssynchrony imaging, echocardiographic and clinical outcomes of left bundle branch pacing and biventricular pacing

“…The latter might occur with bipolar pacing at relatively high output (3.5V), a setting which was always programmed as safety margin during the first month after device implantation. In accordance, Curila et al reported slightly negative (−9 ms) e-DYS in LBBP with anodal capture [ 13 ].…”

The role of conduction system pacing in patients with atrial fibrillation

“…Randomised trials comparing LBBP in SR and AF populations may address this, but given the modest improvements observed in acute electrical outcomes, prohibitively large sample sizes may be required to detect small differences in hard clinical endpoints. Of note, clinical effect sizes may be further diluted by a proportion of patients who exhibit anodal septal capture ( 26 , 50 ). Such patients may not gain electrical benefit from AVD optimisation, as preservation of intrinsic RBB conduction would theoretically not be necessary in such instances.…”

“…These studies demonstrated that LBB capture, whilst leading to accelerated LV lateral wall activation, led to increased interventricular dyssynchrony compared to LV septal myocardial pacing (LVSMP) due to late RV activation. Interestingly, this dyssynchrony was reduced in a proportion patients where bipolar anodal septal capture could be achieved, leading to simultaneous RBB, LV septal and LBB capture, compared to unipolar LBB capture in the same patients ( 26 ).…”

Left bundle branch pacing versus left ventricular septal pacing as a primary procedural endpoint during left bundle branch area pacing: Evaluation of two different implant strategies

“…However, there is still no definitive data about the potential benefits of LBBP vs. LVSP in terms of ventricular electrical activation or clinical outcomes in patients undergoing LBBAP 17–19 . In an observational study, Curila et al evaluated the timing of ventricular activations and estimated ventricular dyssynchrony in 68 patients with bradycardia indications using ultrahigh frequency ECG (UHF‐ECG) 17 .…”