title: Effect of concordance between sites of left ventricular pacing and dyssynchrony on acute electrocardiographic and echocardiographic parameters in patients with heart failure undergoing cardiac resynchronization therapy.
abstract: BACKGROUND
  Wide QRS complexes are associated with left ventricular (LV) dyssynchrony, but an optimal site of LV pacing has not been established.
  
  
  OBJECTIVE
  We hypothesized that concordance between the sites of LV pacing and of latest LV mechanical activation during cardiac resynchronization therapy (CRT) is associated with more favorable acute echocardiographic changes.
  
  
  METHODS
  An analysis of 28 consecutive patients (64+/-15 years, 46% male, 52% ischemic heart disease, LV ejection fraction 0.24+/-0.07, QRS 163+/-22 ms, New York Heart Association > or = 3 93%) implanted with biventricular (BIV) defibrillators was performed. Sites of latest LV activation were determined by tissue Doppler imaging (TDI) and speckle tracking (ST). The site of LV pacing was determined by fluoroscopy in two views. A concordance score (0-5) was created to describe the proximity of the pacing site to the site of the latest mechanical activation.
  
  
  RESULTS
  Compared with the worst concordance score, a perfect score was associated with shorter QRS width with LV (187+/-40 vs. 246+/-8 ms, p= 0.048) and BIV (134+/-19 ms vs. 179+/-39 ms, p = 0.05) but not with right ventricular pacing. A perfect concordance score was also associated with a greater acute reduction in LV volumes in systole (42+/-36 ms 16+/-22 ms, p = 0.068) and diastole (47+/-37 vs. 8+/-31 ml, p = 0.043) 24 h after CRT device implantation.
  
  
  CONCLUSIONS
  A high concordance is associated with shorter QRS width with LV and BIV pacing and greater acute reduction in LV volumes. The effect of concordance on the intermediate and long-term response to BIV pacing deserves further evaluation.
authors.affiliation: Cardiovascular Electrophysiology Section, Cardiovascular Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Maninder
authors.initials: M
authors.lastname: Bedi
authors.forename: Matthew
authors.initials: M
authors.lastname: Suffoletro
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanabe
authors.forename: John
authors.initials: J
authors.lastname: Gorcsan
authors.forename: Samir
authors.initials: S
authors.lastname: Saba
mesh_terms: D000208:Acute Disease; D000368:Aged; D002303:Cardiac Output, Low; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000628:therapy*; D011446:Prospective Studies; D018570:Risk Assessment; D013318:Stroke Volume; D018608:Ultrasonography, Doppler; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000628:therapy*