title: Influence of atrial function and mechanical synchrony on LV hemodynamic status in heart failure patients on resynchronization therapy.
abstract: OBJECTIVE
  The aim of this study was to evaluate atrial and ventricular function in patients undergoing cardiac resynchronization therapy (CRT).
  
  
  BACKGROUND
  Right atrial pacing (AP) in CRT induces delays in electrical and mechanical activation of the left atrium. The influence of atrial sensing (AS) versus AP on ventricular performance in CRT and the mechanisms underlying the differences between AS and AP in CRT have not been fully elucidated.
  
  
  METHODS
  Fifty-five patients with heart failure undergoing CRT for 9 ± 12.5 months and 22 control subjects without heart failure were enrolled. Conventional and tissue Doppler echocardiography was performed to examine atrial and ventricular mechanics and hemodynamic status.
  
  
  RESULTS
  The optimal atrioventricular interval was shorter in AS compared with AP mode (126 ± 19 ms vs. 155 ± 20 ms, p < 0.0001). Left ventricular (LV) outflow tract time-velocity integral (22 ± 7 cm vs. 20 ± 7 cm, p < 0.001), diastolic filling period (468 ± 124 ms vs. 380 ± 93 ms, p < 0.001), and global strain (-32 ± 24% vs. -27 ± 22%, p = 0.001) were greater in AS compared with AP mode. Atrial strain was higher in AS compared with AP mode in the right atrium (-28.2 ± 8.6% vs. -22.6 ± 7.6%, p = 0.0007), interatrial septum (-17.1 ± 6.5% vs. -13.2 ± 5.4%, p = 0.002), and left atrium (-16.4 ± 11.0% vs. -13.6 ± 8.5%, p = 0.02). There was no difference in intraventricular dyssynchrony but significantly lower atrial dyssynchrony in AS compared with AP mode (31 ± 19 ms vs. 42 ± 24 ms, p = 0.0002).
  
  
  CONCLUSIONS
  AS is associated with preserved atrial contractility and atrial synchrony, resulting in optimal LV diastolic filling, stroke volume, and LV systolic mechanics. This pacing mode maximizes LV performance and the hemodynamic benefit of CRT in patients with heart failure.
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Hsin-Yueh
authors.initials: HY
authors.lastname: Liang
authors.forename: Alan
authors.initials: A
authors.lastname: Cheng
authors.forename: Kuan-Cheng
authors.initials: KC
authors.lastname: Chang
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
authors.forename: Kunal
authors.initials: K
authors.lastname: Agarwal
authors.forename: Patrick
authors.initials: P
authors.lastname: Eulitt
authors.forename: Mary
authors.initials: M
authors.lastname: Corretti
authors.forename: Gordon
authors.initials: G
authors.lastname: Tomaselli
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.forename: David A
authors.initials: DA
authors.lastname: Kass
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Abraham
mesh_terms: D000368:Aged; D016279:Atrial Function, Left; D016280:Atrial Function, Right; D015142:Baltimore; D058406:Cardiac Resynchronization Therapy; D016022:Case-Control Studies; D015150:Echocardiography, Doppler; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left