Comparison of the echocardiographic and electrocardiographic parameters of long term left ventricular systolic functions in patients who have VDD and DDD pacemaker implantation

Purpose: VDD pacemaker system is composed of a battery and a lead, that stimulate the ventricle by sensing the atrium, providing synchronized activity between them in case of atrioventricular block. DDD pacemaker system, on the other hand, does this job by two leads in the AV block patients. DDD pacing has become a more preferred modality nowadays, because of the concerns about a possible need for atrial pacing in long term and developments in battery softwares and lead technology. In our study, we aimed to compare the clinical follow ups of patients who previously had a VDD pacemaker implanted to themselves with DDD patients by the clinical information and changes in left ventricular function that we obtain from previous clinical records. Methods: Our study included 1238 VDD or DDD mode patients out of a total number of 2025 pacemaker patients, who came to emergency room or polyclinics of İstanbul Bilim University Department of Cardiology, with a diverse set of clinical situations and had their pacemaker implanted between 1985-2014. Demographic variables and data such as left ventricular systolic functions before and after pacemaker implantation, complications, pacemaker dependencies, follow up times, rhythms before and after pacemaker implantation, potential problems that may be related to pacemakers and additional interventions, valvular pathologies, coronary artery disease, whether a revascularization was performed and data about the clinical follow up were evaluated. Results: There was no significant differences between the groups concerning age, hypertension, diabetes mellitus, heart failure and coronary artery disease (p>0,05). When echocardiographic data was compared, basal EF, end diastolic diameter, end systolic diameter and mean pulmonary artery pressure was similar in the two groups. The left atrial diameter was smaller in VDD patients compared to DDD patients (p=0,05). When mitral regurgitation was classified as mild to moderate and severe, there was a significant difference between the groups, while aortic insufficiency rates were similar. There was a significant decrease of ejection fraction (p<0,001) and increase of LV end systolic diameter (p<0,001), LA size (p<0,001) and systolic PAP (p<0,008) in VDD group. LV end diastolic diameter on the other hand, showed no significant difference when base and control measurements were investigated. Similarly in the DDD group there was a significant decrease in LV EF and increase in LV end diastolic diameter, LA size and systolic PAP levels. (p<0,0001). When statistics were repeated including only the patients whose reason for pacemaker implantation was complete AV block, again a significant decrease in LV EF levels in both pacemaker groups (p>0,0001). When DDD group was divided into two groups according to whether the lead was implanted to RVA and RVNA, RVA group had a significantly higher EF (p<0,05). Both RVA and RVNA groups had a significantly decreased EF in the control echocardiographies when compared to base EFs, with p<0,001 and <0,022 respectively. When rhythms in the last controls of the patients that could be reached were evaluated, VDD patients were the patients who retained their sinus rhythms mostly. On the long term, when we take the complications such as tamponade, infections and pneumothorax into concern, there was no significant difference between the two groups (p>0,05). DDD PM upgrades were performed to 7 patients (%1,5) who previously had a VDD PM implanted. In the comparison of the two groups when EF of 40% and 45% were taken as a cut off level for systolic dysfunction, there was no significant difference. Conclusion: Both VDD and DDD pacemaker patients have LV EF decreases and LV diameter increases on the long term. Clinical surveys and complication frecuencies were not different in the two groups. However, it is observed that when all the patient group was taken into account, DDD mode has shown no advantages over VDD and also shown disadvantages as low battery life or when in the case of atrial fibrillation. In addition to the evaluation of sinus node function, which is the most important criterion for AV block patient in the determination of VDD or DDD, individualized evaluation should be done at patient level. Key words : VDD pacemaker, DDD pacemaker, left ventricular systolic function