Study on Effectiveness and Safety of LBBaP With Solia S and Selectra 3D Developed by BIOTRONIK

Traditional ventricular pacing leads are placed in and around the right ventricular apex (RVA), which are easy to operate. The long-term safety and efficacy of right ventricular pacing (RVP) in the treatment of bradycardia arrhythmia have been demonstrated. However, it is shown by CTOPP (Canadian Trial of Physiologic Pacing) study (1), MOST (Micro-Optical Sectioning Tomography) study (2) and UKPACE (United Kingdom Pacing and Cardiovascular Events) study (3) that long-term and high-proportion right ventricular apical pacing (RVAP) may lead to ventricular systolic asynchrony, and accordingly increase the risks of cardiac failure (cardiac insufficiency) and atrial fibrillation (AF).

The concept of His bundle pacing (HBP) has been put forward for a long time, in which His bundle is directly stimulated to synchronously excite the ventricles mainly through the conduction of the His-Purkinje system (HPS) in the electrical activity of the heart. The study performed by Vijayaman et al. (4) shows that HBP can reduce the long-term mortality and the risks of hospitalization for cardiac failure and upgrading to CRT compared with the traditional RVAP. However, HBP surgery has the following disadvantages: (1) It is rather difficult to fix the leads, the operation duration is long, the suture removal duration is long, and the learning curve of doctors is long; (2) The threshold value is high during implantation and may further increase in the long term, and the sensory power is rather low. Therefore, the implantation of spare leads is recommended in relevant guidelines, increasing the hardware burden in patients; (3) The implantation site of patients with conduction block below His bundle is rather difficult or unable to cross the block site.

In order to improve the HBP surgery, Chinese doctors have put forward LBBaP in recent years, arousing widespread concern all over the world. Dedicated sheath tubes and electrode leads are adopted in the technique. Specifically, electrode leads are "screwed" into the left bundle branch area under the left ventricular intima from the right ventricular septum (RVS), and the left bundle branch pacing (LBBP) is performed to improve bradycardia. Compared with HBP, LBBP has the following advantages: (1) As the implantation site is easier to locate, the operation difficulty is reduced; (2) With a lower and more stable threshold, the sensitivity is better; (3) Distal block is corrected; (4) An enough space is left for atrioventricular junction ablation.

At present, it is collectively known as HBP in the international community. LBBaP refers to conduction system pacing, the performing of which depends on dedicated tools or instruments. In early times, the positioning and fixation of shaping steel wires in combination with active-fixation leads adopted in the technique were realized with the aid of a mapping catheter. The operation success rate of HBP was rather low and LBBaP could not be realized. With the introduction of dedicated sheath tubes by various manufacturers, the operation success rate has been greatly improved. However, there are no enough data derived from large-scale studies at home and abroad on the effectiveness and safety of LBBaP with Selectra 3D and Solia S developed by BIOTRONIK at present.

This study is aimed to assess the effectiveness and safety of LBBaP with Solia S and Selectra 3D in the Chinese population by analyzing the operation success rate and the system stability during follow-up visits.

• Number of participants with abnormal pacing parameters and abnormal ECG readings [Time frame: 1 month and 12 months post-procedure]
• Changes of cardiac ultrasound values (including LVEF, LVESD and LVEDD) [Time frame: 12 months post-procedure.]
• Changes of NYHA class [Time frame: 1 month and 12 months post-procedure]
• Changes of EQ-5D-5L assessment [Time frame: 1 month and 12 months post-procedure]