Atrial Dysfunction and Interatrial Dyssynchrony Predict Atrial High Rate Episodes: Insight into the Distinct Effects of Right Atrial Appendage Pacing

Atrial Dysfunction and Dyssynchrony Predict Atrial High Rate Episodes . Introduction: Right atrial (RA) appendage pacing may prolong atrial conduction time (ACT). This study aimed to investigate if RA appendage pacing can induce intra‐ and interatrial dyssynchrony and if atrial dysfunction and dyssynchrony can predict atrial high rate episodes (AHREs) in the first year after pacing. Methods and Results: Patients implanted with dual‐chamber pacemakers for symptomatic bradycardia were enrolled. Cumulative percentage of RA appendage pacing (Cum%AP) during 1‐year follow‐up and AHREs were recorded. Full Doppler echocardiography studies were performed before implantation and 1 year after pacing. ACT and peak atrial velocities (Sm‐la, Em‐la, Am‐la) were measured. One hundred ten patients (age 70.5 ± 11 years; 53 males) were recruited and completed 1‐year follow‐up. ACT of both RA and left atrial (LA) were more prolonged in patients with Cum%AP > 75% than those with <25%. Intra‐ and interatrial dyssynchrony was more obvious in patients with Cum%AP > 75% (22.3 ± 12.2 milliseconds vs 9.5 ± 6.2 milliseconds; 53.9 ± 29.7 milliseconds vs 19.7 ± 17.3 milliseconds; both P < 0.001). AHREs occurred in 29% of patients. Atrial pump function and interatrial dyssynchrony independently predicted AHREs in multivariate analysis. Receiver operating characteristic curve provided a cutoff value of Am‐la <5.3 cm/s, which predicted AHREs with a sensitivity of 71% and a specificity of 75% (area under the curve, 0.822; P < 0.001). Conclusion: RA appendage pacing causes atrial conduction delay with intra‐ and interatrial dyssynchrony. Atrial dysfunction and interatrial dyssynchrony are related to AHREs in the first year after pacing.