P361Intra- and interatrial dyssynchrony enhanced by right atrial appendage pacing

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Purpose: Right atrial (RA) appendage pacing may prolong atrial conduction time (ACT). The present study aimed to investigate if cumulative percentage of RA appendage pacing (Cum%AP) can enhance intra- and interatrial dyssynchrony in patients with normal ejection fraction after one year pacing.Methods: Patients who are undergoing dual chamber pacemaker implantation due to symptomatic bradycardia were enrolled. Patients with left ventricular ejection fraction <45% and permanent atrial fibrillation were excluded. Cumulative percentage of right ventricular apical pacing (Cum%VP) and Cum%AP at one-year follow was recorded. Full Doppler echocardiography studies were performed before pacemaker implantation and one year follow up. ACT and peak atrial velocities (Sm-la, Em-la and Am-la) were measured. Intra- and interatrial dyssynchrony were calculated.Results: We enrolled 110 patients with mean age of 70.5±11 years. High Cum%AP of more than 75% (Cum%AP >75%) (n=27) over one year were compared to those with low Cum%AP of less than 25% (Cum%AP <25%) (n=43) according to the interquartile range of distribution. There was no significant difference in Cum%VP between these two groups (75.8±38.0 vs. 91.1±24.0%, p=0.069). Atrial velocities were significantly lower and ACT of both RA and left atrial (LA) were more prolonged in patients with Cum%AP >75% than those with <25% (all p<0.05). Intra and interatrial dyssynchrony was more obvious in patients with Cum%AP >75% (RA dyssynchrony: 23.4±21.5 vs. 10.6±10.3ms, p=0.007; LA dyssynchrony: 22.3±12.2 vs. 9.5±6.2ms, p<0.001; interatrial dyssynchrony: 53.9±29.7 vs. 19.7±17.3ms, p<0.001). In the whole cohort, Am-la correlated negatively with LA dyssynchrony (r=-0.450, p<0.001) and interatrial dyssynchrony (r =-0.227, p=0.018). Interatrial dyssynchrony was correlated with Cum%AP (r=0.617, p<0.001) but not with Cum%VP (r=-0.058, p=0.548).Conclusions: RA appendage pacing causes atrial conduction delay with intra- and interatrial dyssynchrony.

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