Effects of optimized left atrioventricular conduction time on hemodynamics and prognosis in patients with third degree atrioventricular block implanted with dual chamber pacemakers
Authors: Zhang Shulan , Qiang Jiaqi , Yue Qingxiong , Li Linan , Yan Peishi , Dong Jing , Qiao Jie , Lin Hailong 
Published: August 2024

<p><strong>Objective:</strong> To investigate the effect of optimized left atrioventricular conduction time (Lavi) on hemodynamics and prognosis of patients with third degree atrioventricular block implanted with dual chamber pacemakers. <strong>Methods:</strong> 120 patients with third degree atrioventricular block implanted with dual chamber pacemaker were randomly divided into Lavi optimized group and non optimized group. Oesophageal electrocardiography was performed 3 months after pacemaker implantation (observation base point). The atrial conduction time (IACT) and interventricular conduction time (IVCT) of the two groups were measured and the Lavi under the default atrioventricular delay (AVD) state of the pacemaker was calculated. The optimization group then adjusted the AVD of the pacemaker under the guidance of echocardiography to obtain the optimal Lavi under the best mechanical synchronization state of the left atrioventricular. All patients were examined by echocardiography at 6, 12 and 18 months after operation. ECG conduction parameters, related clinical manifestations and prognostic indicators were observed, and the relationship between optimal Lavi and heart rate was analyzed. <strong>Results:</strong> a) In the optimization group, the average optimal Lavi was (130.8 ± 11.9) ms, which was longer than the default Lavi value (120.7 ± 18.7ms) (<em>p</em> &lt; 0.05). b) In the optimization group, the optimal Lavi was negatively correlated with heart rate (<em>r</em> = −0.955, <em>p</em> &lt; 0.05), heart rate &lt;70 beats/min, and the optimal Lavi was 140 ms; the heart rate was 70~80 beats/min, and the optimal Lavi was 130ms; heart rate &gt;80 beats/min, and the optimal Lavi is 120 ms. c). Optimization of Lavi could immediately improve e-peak deceleration time (EDT) and isovolumic relaxation time (IVRT) in the optimization group (<em>p</em> &lt; 0.05). d) The left ventricular ejection fraction (LVEF), EDT and IVRT of the optimized group were better than those of the non optimized group at 6 months after operation (<em>p</em> &lt; 0.05), and the left atrial volume index and e/e ‘(the ratio of early diastolic flow velocity of mitral orifice to early diastolic movement velocity of mitral annulus) were better than those of the non optimized group at 12 months after operation (<em>p</em> &lt; 0.05). e) LVEF and EDT in the non optimized group decreased gradually during the follow-up period of 18 months (<em>p</em> &lt; 0.05); IVRT and left atrial volume index increased gradually during the whole follow-up period (<em>p</em> &lt; 0.05). E/e ‘in the optimization group increased gradually during the follow-up period (<em>p</em> &lt; 0.05), while EDT decreased gradually during the follow-up period (<em>p</em> &lt; 0.05). f) The cumulative incidence of new paroxysmal atrial fibrillation in the optimization group was significantly lower than that in the non optimization group (8.3% vs. 23.3%, <em>p</em> &lt; 0.05). Conclusion optimization of Lavi can improve hemodynamics and reduce the incidence of atrial fibrillation in patients with third degree atrioventricular block implanted with dual chamber pacemakers.</p>