title: Integration of mechanical, structural and electrical imaging to understand response to cardiac resynchronization therapy.
abstract: OBJECTIVE
  There is extensive controversy exists on whether cardiac resynchronization therapy corrects electrical or mechanical asynchrony. The aim of this study was to determine if there is a correlation between electrical and mechanical sequences and if myocardial scar has any relevant impact.
  
  
  METHODS
  Six patients with normal left ventricular function and 12 patients with left ventricular dysfunction and left bundle branch block, treated with cardiac resynchronization therapy, were studied. Real-time three-dimensional echocardiography and electroanatomical mapping were performed in all patients and, where applicable, before and after therapy. Magnetic resonance was performed for evaluation of myocardial scar. Images were postprocessed and mechanical and electrical activation sequences were defined and time differences between the first and last ventricular segment to be activated were determined. Response to therapy was defined as a reduction in left ventricular end-systolic volume ≥ 15% after 12 months of follow-up.
  
  
  RESULTS
  Good correlation between electrical and mechanical timings was found in patients with normal left ventricular function (r(2) = 0.88; P = .005) but not in those with left ventricular dysfunction (r(2) = 0.02; P = not significant). After therapy, both timings and sequences were modified and improved, except in those with myocardial scar.
  
  
  CONCLUSIONS
  Despite a close electromechanical relationship in normal left ventricular function, there is no significant correlation in patients with dysfunction. Although resynchronization therapy improves this correlation, the changes in electrical activation may not yield similar changes in left ventricular mechanics particularly depending on the underlying myocardial substrate.
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Etelvino
authors.initials: E
authors.lastname: Silva
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Bart
authors.initials: B
authors.lastname: Bijnens
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Berruezo
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Lluis
authors.initials: L
authors.lastname: Mont
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Adelina
authors.initials: A
authors.lastname: Doltra
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Andreu
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Brugada
authors.affiliation: Servicio de Cardiología, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain. Electronic address: msitges@clinic.ub.es.
authors.forename: Marta
authors.initials: M
authors.lastname: Sitges
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D058406:Cardiac Resynchronization Therapy; D016022:Case-Control Studies; D019560:Echocardiography, Three-Dimensional; D005260:Female; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D018487:Ventricular Dysfunction, Left / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D016277:Ventricular Function, Left / Q000502:physiology
keywords: Acoplamiento electroanatómico; Cardiac resynchronization therapy; Cartografía electroanatómica; Disincronía eléctrica; Disincronía mecánica; Electrical dyssynchrony; Electroanatomic mapping; Electromechanical coupling; Mechanical dyssynchrony; Terapia de resincronización cardiaca