Optimizing the Atrioventricular Delay in Dual Chamber Pacemakers; Is It Worth?

Abstract

Background: The number of patients treated with a dual chamber (DDD) pacemaker is continually increased each year. The Optimal AV synchrony will not only maximize cardiac output by increasing ventricular preload, thus lowering mean atrial pressure, but it will also minimize the diastolic mitral regurgitation. Until now, individualized optimization of the AVI is not performed in the clinical routine. This is mainly because of the time-consuming process of manual optimization and the lack of guideline recommendations. Objective: To assess the optimal AV delay for each patient and to decide whether this optimization is worth doing it for all patients. Patients and methods: After approval of Local Ethics Committee and obtaining written informed consent, a prospective, comparative randomized study was conducted on 56 patients with symptomatic bradyarrhythmia requiring adual chamber pacemaker implantation. All patients were assessed by thorough history taking, clinical examination, 12 lead surface ECG, and Echocardiography, They were randomly divided into two groups. Group A (28 patients): where their AVD was set at the default values, while in group B the AVD was optimized with guidance of the trans-mitral Doppler waves on echocardiography. Then echocardiography follow up was done after 12 months. Results: Statistically significant increase was found in the LVEF in group B from 67.71±4.58 to 73.43±4.74 (p<0.0001) while it was found to decrease in group A from 72.21±6.28 to 69.43±5.41 after 12 months of device implantation (p<0.0001). Similar results were observed as regard the RVEF which decreased non significantly in group A after 12 months from 49.0±5.82 to 48.07±5.13 (p: 0.07), while in group B a significant increase from 48.57±5.1 to 53.14±7.31 was observed (p<0.0001). Confirming these results again by analyzing the total change in LVEF and RVEF after one year and comparing the two groups directly. Both LVEF and RVEF show a highly significant increase in group B in comparison with group A (P<0.0001). Also the LAP decreased significantly in both groups (P<0.001). Conclusion: Optimizing the AVD for all patients of DDD pacemakers may lead to long term beneficial effects mainly on the systolic functions.