title: Baseline vectorcardiography as a predictor of invasively determined acute hemodynamic response to cardiac resynchronization therapy.
abstract: OBJECTIVE
  Identifying potential responders to cardiac resynchronization therapy (CRT) may be sometimes difficult and time consuming. Searching for a simple method, we chose vectorcardiography (VCG) for our study. The aim was to evaluate whether a VCG parameter can be used to predict invasively measured acute hemodynamic changes after CRT onset.
  
  
  RESULTS
  Baseline VCG data were prospectively recorded just before initiation of CRT in a series of 126 consecutive patients (♂74 %, DCMP 60 %, ICMP 40 %, NYHA class III 100 %, QRS width 161 ± 27 ms, LV-EF 25 ± 6.5 %) prior to implantation at our specialized center. The time interval (TI) between the maximum vector and the end of the vector loop (initial description by Koglek W.) was correlated with acute hemodynamic change after CRT onset. Positive response to CRT was defined as an increase in dp/dt max >10 % or pulse pressure >5 %. According to these invasive hemodynamic parameters, 25 patients (20 %) were defined as non-responders. Using ROC analysis, the threshold value of the TI for responders was found to be 64 ms. TI is a predictor of acute hemodynamic response with a sensitivity of 96 %, a specificity of 76 %, a positive predictive value of 94 %, and a negative predictive value of 79 %. More non-responders are identified by TI than by using conventional QRS width in the 12-lead surface ECG.
  
  
  CONCLUSIONS
  TI is a new method of evaluation based on baseline VCG analysis. It may be a useful diagnostic test for predicting acute hemodynamic response to CRT.
authors.affiliation: Herzzentrum Brandenburg in Bernau, Ladeburger Straße 17, 16321, Bernau bei Berlin, Germany. t.schau@immanuel.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Schau
authors.forename: Walter
authors.initials: W
authors.lastname: Koglek
authors.forename: Josef
authors.initials: J
authors.lastname: Brandl
authors.forename: Martin
authors.initials: M
authors.lastname: Seifert
authors.forename: Jürgen
authors.initials: J
authors.lastname: Meyhöfer
authors.forename: Michael
authors.initials: M
authors.lastname: Neuss
authors.forename: Georg
authors.initials: G
authors.lastname: Grimm
authors.forename: Robert
authors.initials: R
authors.lastname: Bitschnau
authors.forename: Christian
authors.initials: C
authors.lastname: Butter
mesh_terms: D000368:Aged; D001794:Blood Pressure; D058406:Cardiac Resynchronization Therapy; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018579:Patient Selection; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D013997:Time Factors; D016896:Treatment Outcome; D014672:Vectorcardiography