title: Gauging the response to cardiac resynchronization therapy: The important interplay between predictor variables and definition of a favorable outcome.
abstract: OBJECTIVE
  Selection of patients who are viable candidates for cardiac resynchronization therapy (CRT), prediction of the response to CRT as well as an optimal definition of a favorable response, all require further exploration. The purpose of this study was to evaluate the interplay between the prediction of the response to CRT and the definition of a favorable outcome.
  
  
  METHODS
  Seventy patients who received CRT were included. All patients met current guideline criteria for CRT. Forty-three echocardiographic parameters were evaluated before CRT and at 1, 3, 6, and 12 months. M-mode, 2D echocardiography, and Doppler imaging were used to quantify left ventricular (LV) systolic and diastolic function, mitral regurgitation, right ventricular systolic function, pulmonary artery pressure, and myocardial mechanical dyssynchrony. The following definitions of a favorable CRT response were used: left ventricular ejection fraction (LVEF) improvement more >5% acutely following CRT, LVEF improvement >20% at 12-month follow-up, and a LV end-systolic volume (LVESV) decrease >15% at 12-month follow-up.
  
  
  RESULTS
  For the LVEF improvement >5%, the best predictor was isovolumetric relaxation time (IVRT; P=.035). For improvement of LVEF >20%, the best predictors were left ventricular stroke index (LVSI; P=.044) and left ventricular fractional shortening (LVFS; P=.031). For the drop in left ventricular systolic volume (LVESV >15%), the best predictor was septal-to-lateral wall delay (ΔT) (P=.043, RR=1.023, 95% CI for RR=1.001-1.045).
  
  
  CONCLUSIONS
  The definition of a favorable CRT response influenced the optimal predictor variable(s). Standardization of defining a favorable response to CRT is needed to guide clinical decision making processes.
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.|School of Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Milan
authors.initials: M
authors.lastname: Petrovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Marija
authors.initials: M
authors.lastname: Petrovic
authors.affiliation: School of Medicine, University of Belgrade, Belgrade, Serbia.|Pacemaker Center, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Goran
authors.initials: G
authors.lastname: Milasinovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.|School of Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Bosiljka
authors.initials: B
authors.lastname: Vujisic Tesic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.|School of Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Danijela
authors.initials: D
authors.lastname: Trifunovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Olga
authors.initials: O
authors.lastname: Petrovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.|School of Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Nedeljkovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Petrovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.|School of Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Marko
authors.initials: M
authors.lastname: Banovic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Marija
authors.initials: M
authors.lastname: Boricic-Kostic
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Petrovic
authors.affiliation: Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA.
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.affiliation: Clinic of Cardiology, Clinical Center of Serbia, Belgrade, Serbia.|Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.
authors.forename: Dejana
authors.initials: D
authors.lastname: Popovic
mesh_terms: D062186:Arterial Pressure / Q000502:physiology; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D015150:Echocardiography, Doppler / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016896:Treatment Outcome; D018754:Ventricular Dysfunction / Q000000981:diagnostic imaging* / Q000503:physiopathology
keywords: cardiac resynchronization therapy; definition of favorable response; predictor variable