A Comparison Of The Long-term Clinical Outcome Between VVI And DDD Pacing

Background:Several studies have indicated that selection of pacing mode may be important for the clinical outcome in patients with symptomatic bradycardia, affecting the development of atrial fibrillation (AF), thromboembolism, congestive heart failure, mortality and quality of life. Previously, many studies suggested that physiologic pacing (dual-chamber) may be superior to single-chamber (ventricular) pacing, because it is associated with lower risks of atrial fibrillation, throm- boembolism, heart failure, death and so on. However, in randomized multicentre trials comparing VVI(R) with DDD(R) pacing, AF, throm- boembolism, congestive heart failure, mortality are only slightly less frequent in the dual-chamber mode. This is most likely due to unnecessary ventricular pacing, which is more frequent in dual-chamber pacing. So, it is still under investigation which kind of pacing mode is the best option for symptomatic bradycardia patients.Objective: The purpose of this study was to compare the long-term outcome of symptomatic bradycardia patients with DDD pacemaker and VVI pacemaker and will give some clinical evidence for the selection of a suitable pacing mode.Methods: Totally, 116 symptomatic bradycardia patients were enrolled, 57 patients with DDD pacemaker and 59 patients with VVI pacemaker. The patients'data were retrospectively analyzed, including the symptoms of patients, holter, echocardiographic examination, electrocardiogram and so on.The observed long-term outcome includes atrial fibrillation, throm- boembolism, hospitalization for heart failure, and death due to cardio- vascular causes or death from any cause.Results: Fifty seven patients with DDD pacemaker were followed up 97.2±27.4 months. Fifty nine patients with VVI pacemaker were followed up 106.6±44.0 months.(1)The incidence of thromboembolism in VVI group is higher than that in DDD group (17.9 % vs. 5.5 %, P<0.005).(2)The incidence of atrial fibrillation was lower among the patients in DDD group than VVI group (5.4% vs 22.7%, P>0.05).(3) The death rate was 11.9 % in VVI group , as compared with 10.5% in DDD group, there is no statistic difference, P>0.05.(4)At the time the final follow-up, the left atrial (LA) in DDD group became larger than pre-implantation. The LA, left ventricular (LV) in VVI group also became larger than pre-implantation. the EF value, LA, LV in VVI group became larger than DDD group. However,the right ventricular between DDD and VVI show no statistic difference.Conclusions: DDD pacing provides more benefit over VVI pacing for the prevention of thromboembolism and left ventricle remodeling, and there is a tendency of lower incidence of atrial fibrillation in DDD patient than VVI patient. DDD pacing may be superior to VVI pacing as to the improvement of the EF value, However, there is no difference between two pacing mode for the risk of death,.