title: Mechanical dyssynchrony or myocardial shortening as MRI predictor of response to biventricular pacing?
abstract: OBJECTIVE
  To investigate whether mechanical dyssynchrony (regional timing differences) or heterogeneity (regional strain differences) in myocardial function should be used to predict the response to cardiac resynchronization therapy (CRT).
  
  
  METHODS
  Baseline mechanical function was studied with MRI in 29 patients with chronic heart failure. Using myocardial tagging, two mechanical dyssynchrony parameters were defined: the standard deviation (SD) in onset time (T onset) and in time to first peak (T peak,first) of circumferential shortening. Electrical dyssynchrony was described by QRS width. Further, two heterogeneity parameters were defined: the coefficient of variation (CV) in end-systolic strain and the difference between peak septal and lateral strain (DiffSLpeakCS). The relative increase in maximum rate of left ventricle pressure rise (dP/dt max) quantified the acute response to CRT.
  
  
  RESULTS
  The heterogeneity parameters correlated better with acute response (CV: r = 0.58, DiffSLpeakCS: r = 0.63, P < 0.005) than the mechanical dyssynchrony parameters (SD(T onset): r = 0.36, SD(T peak,first) r = 0.47, P = 0.01, but similar to electrical dyssynchrony (r = 0.62, P < 0.001). When a heterogeneity parameter was combined with electrical dyssynchrony, the correlation increased (r > 0.70, P incr < 0.05).
  
  
  CONCLUSIONS
  Regional heterogeneity in myocardial shortening correlates better with response to CRT than mechanical dyssynchrony, but should be combined with electrical dyssynchrony to improve prediction of response beyond the prediction from electrical dyssynchrony only.
authors.affiliation: Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Iris K
authors.initials: IK
authors.lastname: Rüssel
authors.forename: Jaco J M
authors.initials: JJ
authors.lastname: Zwanenburg
authors.forename: Tjeerd
authors.initials: T
authors.lastname: Germans
authors.forename: J Tim
authors.initials: JT
authors.lastname: Marcus
authors.forename: Cornelis P
authors.initials: CP
authors.lastname: Allaart
authors.forename: Carel C
authors.initials: CC
authors.lastname: de Cock
authors.forename: Marco J W
authors.initials: MJ
authors.lastname: Götte
authors.forename: Albert C
authors.initials: AC
authors.lastname: van Rossum
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000503:physiopathology*; D011237:Predictive Value of Tests
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA