Abstract: Objective：To evaluate long-term effect of different right ventricular apex pacing ratio for heart structure and function of patients with dual chamber pacemakers. Methods: Patients who were implanted with dual chamber pacemakers at Department of Cardiology, Peking University Third Hospital were collected. The electrodes were put in right ventricular apex. All the patients, last pacemaker programming control and echocardiography results were followed up and collected.Patients with 10%-40% pacing ratio were rejected. Results: The total of 83 patients were enrolled in this study. The mean duration of the followup was (38±23) months. The morbility rates of moderate-severe mitral regurgitation (MR) and tricuspid regurgitation (TR) all significantly increased after implantation compared with those before implantation (6.2% vs. 2.6%, 11.1% vs. 4.9%, all P<0.01). There were 9 patients with moderate-severe TR after pacemaker implantation. They had higher pulmonary artery systolic pressure (PASP) and mitral diastolic early flow peak velocity/lateral mitral annulus diastolic early velocity (E/Em) ［(49.6±10.5) mmHg vs. (33.8±12.0) mmHg, P<0.01, 1 mmHg=0.133 kPa; and 11±5 vs.9±3, P<0.05］. And 52 patients had less than 10% pacing ratio (group A) and 31 patients had more than 40% pacing ratio (group B). The right atrium area and right ventricular diastolic diameter were bigger after implantation than those before implantation in group B ［(17.7±4.0) cm² vs. (15.6±3.2) cm², (21.5±4.4) mm vs. (19.9±3.4) mm, all P<0.05］. The morbility of pulmonary artery systolic pressure (PASP) ≥50 mmHg was higher after implantation than that before implantation in group B (9.7% vs. 3.2%, P<0.05). The left atrium area and right atrium area were bigger in group B than those in group A ［(21.8±5.5) cm² vs. (20.2±4.6) cm², (17.7±4.0) cm² vs. (16.1±3.8) cm², all the P<0.05］ after implantation, and lower left ventricular ejection fraction (LVEF) in group B than that in group A (68%±6% vs. 70%±6%, P<0.05). Conclusion: Patients with higher right ventricular apex pacing ratio have bigger left atrium, right atrium and right ventricular, higher PASP and lower LVEF in the long term.

Key words: Arrhythmias, Cardiac pacing, artificial, Ventricular function, right, Atrial function, right