Atrial Synchrony Evaluation of Bachmann Bundle Pacing in Sick Sinus Syndrome

Inclusion Criteria: * Meets diagnostic criteria for sick sinus syndrome (e.g., persistent sinus bradycardia \<50 bpm, sinus arrest, sinoatrial block, or tachy-brady syndrome). * Age between 30 and 90 years. * Has not taken any other antiarrhythmic drugs within one month prior to enrollment. * Has not participated in any other related clinical trials. * Voluntarily signs the informed consent form. Exclusion Criteria: * Patients with severe primary diseases causing unstable vital signs (e.g., severe circulatory, digestive, or neurological system diseases). * Patients with a history of recurrent syncope, Adams-Stokes syndrome, severe bradycardia (lowest sinus rhythm \<30 bpm), or long RR interval \>3s. * Pregnant or lactating women. * Patients with mental illness.