LLL vs. SDL for LBBP: A Non-inferiority RCT

• SDL implantation (Procedure): Implantation of an SDL during LBBP procedures guided by continuous pacing monitoring, with the presence of S-V dissociation serving as the criterion for confirming optimal LBB lead positioning.
• LLL implantation (Procedure): Implantation of an LLL during LBBP procedures guided by continuous pacing monitoring, with the presence of S-V dissociation serving as the criterion for confirming optimal LBB lead positioning.

Primary outcomes

• The primary efficacy endpoint [During the LBBP procedure]: The primary efficacy endpoint is defined as the success rate of intraoperative implantation of the left bundle branch lead with the documentation of S-V dissociation.
• The primary safety endpoint [From start of the procedure to the end of follow-up at 6 months]: The primary safety endpoint is defined as a composite endpoint consisting of the following anticipated procedure-related serious adverse events (SAEs).

Secondary outcomes

• Procedural success rate [During the procedure.]: The procedural success rate, defined as completion of LBB lead implantation in the interventricular septum, meets the criteria for left bundle branch area pacing as defined in current guidelines. Although S-V dissociation is not achieved, at least two visualized indicators are observed when the pacing output is set at ≤2 V/0.5 ms.
• Abnormal parameters detected during follow-up [From the start of procedure to the end of follow-up at 6 months]: Clinically significant abnormalities in pacing lead parameters detected during pacemaker programming throughout the follow-up period.
• Assessment of cardiac function during follow-up [From the start of procedure to the end of follow-up at 6 months]: Postoperative occurrence of pacemaker-related heart failure or progression of pre-existing cardiac insufficiency.
• Assessment of quality of life. [From the start of procedure to the end of follow-up at 6 months]: Changes in subjects' quality of life (assessed by the multipurpose short-form \[SF-12\] Health Survey Score). The SF-12 scale assesses eight health domains. Its standardized scores range from 0 to 100, and a higher total score indicates better overall health status.

Sex: All

Inclusion Criteria:

* Symptomatic sick sinus syndrome (SSS);
* Complete or advanced atrioventricular block (AVB);
* Patients with heart failure complicated by left bundle branch block (LBBB) and biventricular dyssynchrony;
* Patients with atrial fibrillation (AF) complicated by refractory rapid ventricular rate who are scheduled for atrioventricular node ablation and permanent pacemaker implantation;
* Other patients who meet the indications for dual-chamber pacemaker implantation as specified in current guidelines

Exclusion Criteria:

* Patients who are ineligible for transvenous cardiac pacemaker implantation due to anatomical abnormalities, infections, or other factors;
* Patients with existing implantable cardiac electronic devices (ICEDs);
* Patients who opt for right-sided venous access for any reason;
* Patients with an expected survival of less than 1 year;
* Patients who have been enrolled in other clinical trials related to implantable cardiac electronic devices within 3 months prior to enrollment in this study.

• Results publication: Shen J, Jiang L, Wu H, Cai X, Zhuo S, Pan L. A Continuous Pacing and Recording Technique for Differentiating Left Bundle Branch Pacing From Left Ventricular Septal Pacing: Electrophysiologic Evidence From an Intrapatient-Controlled Study. Can J Cardiol. 2023 Jan;39(1):1-10. doi: 10.1016/j.cjca.2022.09.008. Epub 2022 Sep 14. PMID 36113707
• Results publication: Shen J, Jiang L, Wu H, Zhang L, Li H, Pan L. Electrophysiological characteristics of lead position-dependent electrogram uninterrupted transition during left bundle branch pacing. Heart Rhythm. 2025 May;22(5):1279-1288. doi: 10.1016/j.hrthm.2024.10.062. Epub 2024 Nov 6. PMID 39515497
• Results publication: Wu H, Jiang L, Chen W, Zhuo S, Shen J, Zhang L, Zhang Y, Peng X. Short- to Mid-Term Efficacy and Safety of Left Bundle Branch Pacing Guided by Continuous Uninterrupted Paced Intracardiac Electrogram Monitoring Targeting Transition to Selective Left Bundle Branch Capture. J Cardiovasc Electrophysiol. 2025 Nov;36(11):2839-2848. doi: 10.1111/jce.70054. Epub 2025 Aug 19. PMID 40831032
• Results publication: Shen J, Jiang L, Wu H, Li H. Continuous Pacing and Recording Technique: A Real-Time Feedback Approach for Left Bundle Branch Pacing. CJC Open. 2025 Jul 22;7(10):1357-1365. doi: 10.1016/j.cjco.2025.07.008. eCollection 2025 Oct. PMID 41180340