Immediate clinical outcomes of left bundle branch area pacing vs conventional right ventricular pacing

Abstract Background Left bundle branch area pacing (LBBaP) is a new physiological pacing strategy that produces comparable clinical effects to His bundle pacing (HBP). Objective The purpose of this study was to investigate the immediate clinical outcomes of LBBaP vs RVP. Methods and Results From April 2018 to September 2018, we included 44 patients under continuous pacemaker implantation. Patients were randomly divided into the LBBaP group and conventional RVP group. Compared to the RVP group, the LBBaP group displayed significantly increased operative (90.10 ± 19.68 minutes vs 61.57 ± 6.62 minutes, P < .001) and X‐ray exposure times (15.55 ± 5.62 minutes vs 4.67 ± 2.06 minutes, P < .001). The lead threshold of the LBBaP group was increased (0.68 ± 0.20 mV vs 0.51 ± 0.0 mV, P = .001), while the R‐wave amplitude and ventricular impedance did not significantly differ between the two groups. The conventional RVP procedure significantly widened the QRS complex (93.62 ± 8.28 ms vs 135.19 ± 12.21 ms, P = .001), whereas the LBBaP had no effect on QRS complex (130.13 ± 43.30 ms vs 112.63 ± 12.14 ms, P = .904). Furthermore, the LBBaP procedure significantly narrowed the QRS complex in patients with left bundle branch block (LBBB) (168.43 ± 38.870 ms vs 119.86 ± 6.69 ms, P = .019). Conclusion LBBaP is a new physiological, safe and effective pacing procedure with a high overall success rate. Compared to conventional RVP, LBBaP can correct LBBB, thereby improving cardiac electrical dyssynchrony.

also RVP increase the hospitalization rate of heart failure and mortality in the patients with high pacing ratio. [2][3][4] Although clinical experts have attempted pacing multiple positions (apical, interval, right ventricular outflow tract) in the right ventricle, these do not lead to physiological pumping of the heart and so the clinical effect does not make a difference. 5 Deshmukh et al 6 first reported His bundle pacing (HBP) as a safe and effective physiological pacing method in patients with chronic AF. Since then, a number of clinical studies have demonstrated its feasibility and effectiveness, the indications of which are expanding. [7][8][9][10][11] Consequently, HBP is currently recognized as a major physiological pacing method. However, several shortcomings of HBP have been identified in clinical practice, including a high pacing threshold, lead dislocation rate, and low success rate among pacemaker implantation methods, particularly in patients with conduction block at sites distant from His bundle. 9,12,13 Huang et al 14 first created the Left bundle branch area pacing (LBBaP) procedure. A total of 3830 pacing lead was positioned in standard his pacing location, noting His potential, the lead was then advanced into the interventricular septum to reach the left bundle branch area (LBBa), in which allowing a lower output to correct LBBB to achieve physiological pacing. The lead parameters using this procedure after 1 year of follow-up remained favorable. Medtornic inc.
3830 lead when used in introduction, this is done later in the paper, but should be used throughout to identify pacing lead being used. In this context, this study detailed the operation procedure and criteria of LBBaP and also provided a comparison of this procedure to RVP.

| LBBaP implantation
The LBBap lead was initially placed into typical his-bundle pacing region, which was performed as described for the HBP method. 11,12,14 Briefly, with the aid of the C315 sheath (Medtronic Inc., Minneapolis, Minnesota), the selected Secure lead (model 3830, Medtronic, Inc.) was inserted into the His bundle, and then His potential was mapped and recorded first in right anterior oblique (RAO) 30 . Subsequently, the 3830 lead and C315 sheath were pushed together clockwise in the ventricular apex direction (1-3 cm)( Figure 1G). When the 2 V output was unipolar paced by the tip of 3830 lead, the V1 QRS wave appeared W-shaped, which was used as the ideal lead insertion point

| RV pacing
RV leads were implanted in a standard fashion at the RV apex or septum.

| Statistics analyses
SPSS version 19.0 (IBM, Armonk, New York) was used for all statistical analyses. Normally distributed continuous data were expressed as the mean ± SD. Categorical data were described as the number (%) and χ 2 test or Fisher's exact test (if the sample size was less than 40 or the minimum theoretical frequency was less than 1) and used to examine the aforementioned differences. All the tests were twosided. A P-value < .05 was considered statistically significant.

| Study group
A total of 44 consecutive patients were enrolled and divided into two groups by the methods of RV lead implantation, that is, RVP and LBBaP groups. In the LBBaP group, 23 patients underwent pacing in the LBBa region, among which the surgery was successful in 20 patients (87.0%). A total of three patients (13.0%) failed LBBaP The basic criteria of left bundle branch area pacing (LBBaP). A, P potential can be seen in intracardiac electrogram and the duration of P-QRS was 21 ms (P potential to the onset of QRS); B. The duration of QRS <120 ms (119 ms); C and D. The morphology (the left anterior branch block) and duration of the stimulus to the ventricular activation peak (S-Vmax) was similar between selective and non-selective pacing

| Implantation results
Among the 20 patients who successfully underwent LBBaP surgery, 19 (95%) were implanted with dual-chamber pacemaker and

| ECG characteristics
We compared the electrocardiogram (ECG) parameters before and after surgery. In the LBBaP group (n = 20), the QRS wave narrowed  (Table 3 and Appendix S1).

| DISCUSSION
This study described a new physiological pacing procedure known as LBBaP, first reported by Huang et al. 14 In this study, we analyzed the safety and efficacy of LBBaP in a larger group of patients (n = 23) and compared it to traditional RV pacing.
The main findings were that (a) LBBaP is a safe and effective physiological pacing procedure with a high success rate (87.0%), and