This is a prospective, single-center study of patients with an indication for ventricular pacing who attempted LBBP without electrophysiology recording system (EP system).

Patients who meet the inclusion and exclusion criteria will be enrolled into the study. In the study, the implanter was blinded to EP system, only refer to ECG monitoring. The transition of QRS morphology from S-LBBP (or LVSP) to NS-LBBP, abrupt shortening of Stim-LVAT in lead V5, combined with LV septal-derived PVCs and obvious LBB potential in pacing system analyzer were recorded to help the implanter confirm LBB capture. Meanwhile, the technician recorded the data by EP system and evaluated the consistency of the judgment. The primary endpoints included the success rate, procedure-related information, parameters and complications during 3-month follow-up.

Inclusion Criteria:

• (1) requiring ventricular pacing; (2) older than 18 years; (3) signed informed consent.

Exclusion Criteria:

• (1) acute anterior myocardial infarction; (2) intraventricular conduction delay (IVCD); (3) ventricular septal hypertrophy (end-diastolic thickness over 15 mm).

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