Abstract Body (Do not enter title and authors here): Background
Left bundle branch area pacing (LBBAP) has been persuasively adopted in clinical practice to achieve electrical and mechanical synchrony of the left ventricle. However, LBBAP in amyloid light chain cardiac amyloidosis (AL-CA) patients has not been studied in detail.

Hypothesis
LBBAP could be a feasible and safe approach to rectify the conduction system diseases of AL-CA patients.

Aim
To study the feasibility and safety of LBBAP in AL-CA patients.

Methods
Consecutive patients with AL-CA and newly implanted pacemaker in our centre between 1st January 2022 and 31st December 2023 were retrospectively included. The diagnosis of AL-CA was confirmed according to the current ESC position statement. Indications for pacemaker fulfilled the current ESC guideline. All patients underwent attempts of LBBAP or right ventricular pacing (RVP) based on operators’ preference.

Results
A total of 10 patients were included. RVP was chosen initially in 1 patient and LBBAP was attempted in 9 patients. LBBAP were successfully performed in 6 patients (66.7%, 6/9). Three patients crossed over to RVP group because LBBAP was failed to achieve (Fig.1).
Baseline clinical characteristics and pacing parameters was compared between LBBAP group and RVP group (Table.1). Duration of intrinsic QRS was similar and paced QRS was wider in RVP group (P=0.029).
During follow-up, one patient in LBBAP group died from sudden death 15 days after implantation, while 2 patients in RVP group died from sudden death and pneumonia 55 days and 17 days after implantation, respectively. Seven patients visited our centre at three-month follow-up without adverse events and interrogation reports were summarized in Fig.1.

Conclusion
LBBAP appears to be a reasonable method for physiological pacing for patients with AL-CA and bradycardia, but its impact on long-term prognosis needs further investigation.