title: Left ventricular strain patterns in dilated cardiomyopathy predict response to cardiac resynchronization therapy: timing is not everything.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) is not uniformly helpful in heart failure, and the determination of baseline dyssynchrony does not improve its success rate. The aim of this study was to develop prediction rules for successful CRT on the basis of mechanical strain patterns of left ventricular function rather than just the timing of activation.
  
  
  METHODS
  Seventy-six patients had CRT devices implanted from 2003 to 2006 and underwent echocardiography before and after device implantation.
  
  
  RESULTS
  Responders (n = 44), determined by >or=10% improvement in ejection fraction and/or >or=15% decrease in end-systolic volume, and nonresponders (n = 32) had similar baseline clinical and echocardiographic characteristics, which improved only in responders. Resynchronization was achieved in both groups. Two-dimensional speckle-tracking longitudinal strain patterns were correlated with response. The absence of passive compliant segments (>or=+5% holosystolic stretching) was 98% sensitive, 88% specific, and had positive and negative predicting values of 91% and 97%, respectively, for response. Adding the presence of lateral delay to this model increased sensitivity to 100% and specificity to 94%.
  
  
  CONCLUSIONS
  Left ventricular strain patterns are highly predictive of response to CRT.
authors.affiliation: University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Shemy
authors.initials: S
authors.lastname: Carasso
authors.forename: Harry
authors.initials: H
authors.lastname: Rakowski
authors.forename: Klaus K
authors.initials: KK
authors.lastname: Witte
authors.forename: Paul
authors.initials: P
authors.lastname: Smith
authors.forename: David
authors.initials: D
authors.lastname: Carasso
authors.forename: Patrick
authors.initials: P
authors.lastname: Garceau
authors.forename: Zion
authors.initials: Z
authors.lastname: Sasson
authors.forename: John D
authors.initials: JD
authors.lastname: Parker
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000517:prevention & control*