Factors Affecting Selection of Leadless Pacemaker and Atrioventricular Synchronous Pacing Status

Traditional pacemakers consist of a pulse generator and leads. Infections of the pulse generator pocket and lead-related complications are unavoidable issues in the application oftraditional pacemakers.Leadless pacemakers have emerged to address complications associated with the pacemaker pocket and leads in specific patients.The initial design of leadless pacemakers focused on single-chamber (right ventricular)sensing and pacing,However, patients with sinus rhythm may experience pacemakersyndrome symptoms due to atrioventricular desynchrony. Furthermore, a high proportion of atrioventricular dyssynchronous ventricular pacing might increase hospitalization rates for atrial fibrillation and heart failure.Recent developments in leadless dual-chamber pacemakersutilize a built-in triaxial accelerometer.This study aims to investigate factors considered by patients with atrioventricular block and clinical pacemaker implanting physicians when make sure the use of Micra AV. 2). It also seeks to evaluate the atrioventricular synchrony of Micra AV pacing in patients during both exercise and rest, while analyzing factors that influence the AV synchrony.For all screened patients, a questionnaire is required to be finished with data including age, gender, occupation, educational level, clinical history, comorbidities, previous infections, history of implanted electronic devices, economic status, and medical insurance conditions. At same time, all physicians are asked to complete a questionnaire for analyzing the factors influencing the decision of device option.An ambulatory electrocardiogram will be performed at 3 months, 6 months, and 1 year follow-up after device implantation. Data regarding the proportion of atrioventricular Research Protocol Template (Observational Study)\_V1.0\_2023.10.04 7/10 synchrony, atrial sensing atrial contraction mechanical wave (A4) threshold, ventricular pacing threshold, sensing, and impedance will be tested and collected. Postoperative exercise related symptoms and adverse events will be routinely tracked.

• Immediate success rate of Micra AV implantation. [Time frame: During implantation on day 0]
• The percentage of atrioventricular synchrony at 6, 12 months after Micra AV implantation. [Time frame: 6, 12 months post-implant]
• Ventricular pacing threshold, at 3 months, 6 months, and 1 year after Micra AV implantation. [Time frame: 3, 6, 12months post-implant]
• Ventricular sensing at 3 months, 6 months, and 1 year after Micra AV implantation. [Time frame: 3, 6, 12 months post-implant]
• Impedance at 3 months, 6months, and 1 year after Micra AV implantation. [Time frame: 3, 6, 12 months post-implant]
• Major complications related to the device implantation at perioperative period, and 3, 6, 9, 12 months after Micra AV implantation [Time frame: Days 0,1 and 3, 6, 9, 12 months post- implant]
• All-cause mortality rates at 3 months, 6 months, and 1 year after Micra AV implantation. [Time frame: 3, 6, 9, 12 months post-implant]
• Rehospitalization events related to heart failure at 3 months, 6 months, and 1year after Micra AV implantation. [Time frame: 3, 6, 12 months post-implant]
• Tachycardia related to the pacemaker, or adverse events related to the device or algorithm at 3, 6, 12 months after Micra AV implantation. [Time frame: 3,6,12 months post-implant]
• Left venriculat ejection fraction measured by echocardiography at 6, 12 months after Micra AV implanted [Time frame: 6, 12 months post-implant]
• Left ventricular end-diastolic diameter measured by echocardiography at 6, 12 months after Micra AV implantation. [Time frame: 6, 12 months post-implant]
• Parameter adjustment events related to the synchrony less than 70% at 3, 6, 12 months after Micra AV implantation.. [Time frame: 3, 6, 12months post-implant]