e0559 Effects of long-term right ventricular apical pacing on left ventricular remodelling and cardiac function

Objectives To investigate the impacts of long-term right ventricular apical pacing on the ventricular remodelling and cardiac functions of patients with high-grade and third-degree atrioventricular blockage with normal heart structures and cardiac functions. In addition, we provide evidences for choosing an optimal electrode implantation site. Methods Study participants included patients who were admitted for pacemaker replacements and who revisited for examinations of implated pacemakers at outpatient. Pacemakers were implanted to treat high-grade and third-degree atrioventricular blockage. At the time of pacemaker implantation, patients had normal cardiac functions and showed no serious heart diseases or cardiac dilatation. The durations from the implantation to follow-up were more than 5 years. The pacing rate was higher than 80%. Patients with a left ventricular ejection fraction (LVEF) 55 mm were excluded. Ventricular remodelling was defined as: increase of LVEDD by 10% and a reduction of LVEF by 25% 5 years after implantation. Cardiac functions were evaluated according to the New York Heart Association (NYHA) classification. Results A total of 82 patients with a mean age of 66.97±13.19 years (range, 12–91 years old), including 39 male and 43 female were enrolled in this study. The average duration between two assessments was 8.7 years (104.4 months). Before pacemaker implantation, the average left atrial diameter (LA), LVEDD and LVEF were 37.0 mm, 50.23 mm and 64.87%, respectively. After the implantation, these values were 39.39 mm (p=0.000163), 50.82 mm (p=0.177842) and 60.50% (p=0.000104), respectively. 4 patients (4.87%) had ventricular remodelling with deteriorations of cardiac function. Among them, three patients had anterior wall myocardial infarction after implantation and one had type II diabetes. Clinical heart failure symptoms were not found in the patients who did not exhibit ventricular remodelling. Conclusion Through a long period follow-up study, we found that long-term right ventricular apical pacing in patients with normal heart structure and cardiac function generally would not cause ventricular remodelling and clinical deteriorations of cardiac function. Right ventricular apical is a safe and effective site for pacing electrode wire implantation.