title: Atrial dysfunction and interatrial dyssynchrony predict atrial high rate episodes: insight into the distinct effects of right atrial appendage pacing.
abstract: BACKGROUND
  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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors: Institute of Vascular Medicine and Division of Cardiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, People's Republic of China.
authors: Jun-Min
authors: JM
authors: Xie
authors: Fang
authors: F
authors: Fang
authors: Qing
authors: Q
authors: Zhang
authors: Joseph Y-S
authors: JY
authors: Chan
authors: Gabriel W-K
authors: GW
authors: Yip
authors: John E
authors: JE
authors: Sanderson
authors: Yat-Yin
authors: YY
authors: Lam
authors: Bryan P-Y
authors: BP
authors: Yan
authors: Cheuk-Man
authors: CM
authors: Yu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020517:Atrial Appendage / Q000503:physiopathology*; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D016279:Atrial Function, Left; D016280:Atrial Function, Right; D001919:Bradycardia / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects* / Q000379:methods; D016009:Chi-Square Distribution; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006723:Hong Kong; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013997:Time Factors; D016896:Treatment Outcome