title: Electrocardiographic versus echocardiographic optimization of the interventricular pacing delay in patients undergoing cardiac resynchronization therapy.
abstract: BACKGROUND
  Echocardiographic optimization of the VV interval may improve CRT response, but it is time-consuming and not routinely performed. The aim of this study was to compare the response to cardiac resynchronization therapy (CRT) when the interventricular pacing (VV) interval was optimized by tissue Doppler imaging (TDI) to CRT response when it was optimized following QRS width criteria.
  
  
  RESULTS
  The study included 156 consecutive CRT patients with severe heart failure and left bundle-branch block configuration. Atrioventricular interval was selected according to a pulsed Doppler assessment, and VV optimization was randomly assigned to echocardiography (ECHO group, n = 78) or electrocardiography (ECG group, n = 78). Optimal VV was defined for the ECHO group as producing the best LV intraventricular synchrony according to TDI displacement curves and for the ECG group as resulting in the narrowest QRS measured from the earliest deflection. At 6-month follow-up, percentage of echocardiographic responders (defined as neither death nor heart transplantation and a LV end-systolic volume reduction >10%) was higher in the ECG optimized group (50.0% vs 67.9%; P = 0.023), whereas clinical response (defined as neither death nor heart transplantation and >10% improvement in the 6-minute walking test) was similar in both groups (71.8% vs 73.1%; P = 0.858).
  
  
  CONCLUSIONS
  VV optimization based on QRS width obtained a higher percentage of responders in terms of LV reverse remodeling compared to the TDI method.
authors.affiliation: Thorax Institute, Hospital Clínic, Universitat de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Catalonia, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Tamborero
authors.forename: Barbara
authors.initials: B
authors.lastname: Vidal
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Tolosana
authors.forename: Marta
authors.initials: M
authors.lastname: Sitges
authors.forename: Antonio
authors.initials: A
authors.lastname: Berruezo
authors.forename: Etelvino
authors.initials: E
authors.lastname: Silva
authors.forename: Mángeles
authors.initials: M
authors.lastname: Castel
authors.forename: Mariona
authors.initials: M
authors.lastname: Matas
authors.forename: Elena
authors.initials: E
authors.lastname: Arbelo
authors.forename: Jose
authors.initials: J
authors.lastname: Rios
authors.forename: Julián
authors.initials: J
authors.lastname: Villacastín
authors.forename: Josep
authors.initials: J
authors.lastname: Brugada
authors.forename: Lluís
authors.initials: L
authors.lastname: Mont
mesh_terms: D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D016009:Chi-Square Distribution; D018619:Echocardiography, Doppler, Pulsed; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D016015:Logistic Models; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function; D013030:Spain; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling; D016138:Walking