Dual-chamber cardiac pacing effect on left and right atria morphometric parameters and function

Abstract

Abstract Background Dual-chamber pacemaker implantation is a standard interventional treatment strategy for atrioventricular block (AVB) and sick sinus syndrome (SSS). It has been proven that a high percentage of right ventricular pacing might have detrimental effects on cardiac function. However, there is a lack of data on atrial pacing effect on left (LA) and right (RA) atria function. Purpose To assess the impact atrial pacing on left and right atria morphologic and functional parameters in patients after dual-chamber pacemaker implantation. Methods We conducted a prospective study that included patients who received a dual-chamber pacemaker for an indication of AVB or SSS. After signing of the informed consent pacemaker was programmed for base rate of 40 bpm and no rate response in case of clear AVB indication or for base rate of 60 bpm and rate response if indication was SSS. An transthoracic echocardiography was done the next day after pacemaker implantation and after one month at follow up (FU). During the FU the atrial pacing (AP) and ventricular pacing (VP) percentage were captured. To exclude the impact of right ventricular pacing, patients with high VP percentage (>40%) were excluded from analysis. Patients were divided into two groups – group A with high AP (>50%), and group B – low AP (<50%). LA expansion fraction reflecting reservoir function, emptying – reflecting conduit, and active emptying reflecting “atrial kick” were analysed. To compare means the Mann Whitney U test, and for categorical variables – X2 test were used. Results A total of n=100 patients underwent dual-chamber implantation and signed informed consent. Due to significant structural heart disease or reduced ejection fraction (<50%) 11 patients were excluded. Out of those, n=30 were excluded due to a high VP percentage. Group consisted of n=28 and group B of – n=31 patients. Average AP in group A was 66.2% and 5.0% in group B. The mean age (group A 73.6 SD 8.8 years vs group B 79.2 SD 7.3 years, p=0.197), gender distribution (group A males 45.5% vs group B 50.0%, p=0.773), and mean BMI (group A 26.5 SD 4.7 kg/m2 vs group B 29.2 SD 3.3 kg/m2, p=0.191) did not differ significantly between the two groups. The baseline LA and RA morphometric and functional parameters presented in figure 1 and did not differ significantly between the two groups. The change in LA and RA functional parameters presented in figure 2. Even though it did not reach statistical significance, a tendency for lower LA expansion fraction, active emptying fraction and LA ejection fraction were observed in group A. RA morphometric parameters did not change significantly between the two groups at FU. Conclusion A higher percentage of atrial pacing in dual-chamber pacemaker population could lead to impaired LA function over time. Though, longer observational period is needed. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2