not-yet-known not-yet-known not-yet-known unknown 2.1 Background The impact of leadless pacemaker (LP) implantation on valvular and cardiac function remains controversial. This study aims to examine the cardiac and valvular functions before and after the implantation of the LP at our centre and to identify possible influencing factors. 2.2 Methods and results We included patients who underwent their first Micra LP implantation at our center from March 2019 to September 2023. These patients received transthoracic echocardiography (TTE) on average 361 days post-operation. We included 56 patients who underwent LP implantation, of which 15 (26.8%) LPs were placed in the low septum, 37 (66.1%) in the mid septum, and 4 (7.1%) in the high septum of the RV. Approximately one year after implantation, 10 patients (17.9%) experienced more severe of tricuspid regurgitation (TR). However, no significant differences were observed in tricuspid, mitral, or aortic valve regurgitation before and after the procedure. There was a slight improvement in LVEF [59.0 (IQR: 56.9-60.4) vs. 60.0 (IQR: 57.9-62.4) %, p=0.035] and a reduction in left ventricular end-diastolic diameter [5.1 (IQR: 4.7-5.3) vs. 4.80 (IQR: 4.6-5.2) cm, p=0.014] after procedure. Compared to the unchanged TR group, the TR progression group had a higher age [67.0 (IQR: 55.0-76.0) vs. 84.5 (IQR: 74.5-90.5) years, p=0.001] and longer procedure times [50.0 (IQR: 40.0-62.5) vs. 62.5 (IQR: 58.8-76.3) minutes, p=0.044]. Additionally, advanced age [OR: 1.2 (1.1-1.3), p=0.005] and longer procedural time [OR: 1.1 (1.0-1.1), p=0.030] were identified as independent predictors of TR. 2.3 Conclusions Placing the Micra LP in the septum of the RV can potentially improve left heart function and structure. Mid or lower septal implantation might be a preventive measure against TR worsening post-procedure. The primary causes of TR deterioration are advanced age and extended procedural duration.