title: A prospective evaluation of cardiovascular magnetic resonance measures of dyssynchrony in the prediction of response to cardiac resynchronization therapy.
abstract: BACKGROUND
  Many patients with electrical dyssynchrony who undergo cardiac resynchronization therapy (CRT) do not obtain substantial benefit. Assessing mechanical dyssynchrony may improve patient selection. Results from studies using echocardiographic imaging to measure dyssynchrony have ultimately proved disappointing. We sought to evaluate cardiac motion in patients with heart failure and electrical dyssynchrony using cardiovascular magnetic resonance (CMR). We developed a framework for comparing measures of myocardial mechanics and evaluated how well they predicted response to CRT.
  
  
  METHODS
  CMR was performed at 1.5 Tesla prior to CRT. Steady-state free precession (SSFP) cine images and complementary modulation of magnetization (CSPAMM) tagged cine images were acquired. Images were processed using a novel framework to extract regional ventricular volume-change, thickening and deformation fields (strain). A systolic dyssynchrony index (SDI) for all parameters within a 16-segment model of the ventricle was computed with high SDI denoting more dyssynchrony. Once identified, the optimal measure was applied to a second patient population to determine its utility as a predictor of CRT response compared to current accepted predictors (QRS duration, LBBB morphology and scar burden).
  
  
  RESULTS
  Forty-four patients were recruited in the first phase (91% male, 63.3 ± 14.1 years; 80% NYHA class III) with mean QRSd 154 ± 24 ms. Twenty-one out of 44 (48%) patients showed reverse remodelling (RR) with a decrease in end systolic volume (ESV) ≥ 15% at 6 months. Volume-change SDI was the strongest predictor of RR (PR 5.67; 95% CI 1.95-16.5; P = 0.003). SDI derived from myocardial strain was least predictive. Volume-change SDI was applied as a predictor of RR to a second population of 50 patients (70% male, mean age 68.6 ± 12.2 years, 76% NYHA class III) with mean QRSd 146 ± 21 ms. When compared to QRSd, LBBB morphology and scar burden, volume-change SDI was the only statistically significant predictor of RR in this group.
  
  
  CONCLUSIONS
  A systolic dyssynchrony index derived from volume-change is a highly reproducible measurement that can be derived from routinely acquired SSFP cine images and predicts RR following CRT whilst an SDI of regional strain does not.
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. manav.sohal@gstt.nhs.uk.|The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK. manav.sohal@gstt.nhs.uk.|Division of Imaging Sciences, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, London, SE1 7EH, UK. manav.sohal@gstt.nhs.uk.
authors.forename: Manav
authors.initials: M
authors.lastname: Sohal
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. simonduckett@yahoo.co.uk.
authors.forename: Simon G
authors.initials: SG
authors.lastname: Duckett
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK. x.zhaung@ucl.ac.uk.
authors.forename: Xiahai
authors.initials: X
authors.lastname: Zhuang
authors.affiliation: Biomedical Image Analysis Group, Department of Computing, Imperial College London, London, UK. trustswz@gmail.com.
authors.forename: Wenzhe
authors.initials: W
authors.lastname: Shi
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. m.ginks@btinternet.com.
authors.forename: Matthew
authors.initials: M
authors.lastname: Ginks
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. anoopshetty@doctors.org.uk.|The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK. anoopshetty@doctors.org.uk.
authors.forename: Anoop
authors.initials: A
authors.lastname: Shetty
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. eva.sammut@kcl.ac.uk.
authors.forename: Eva
authors.initials: E
authors.lastname: Sammut
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. kozerke@biomed.ee.ethz.ch.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kozerke
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. steven.niederer@kcl.ac.uk.
authors.forename: Steven
authors.initials: S
authors.lastname: Niederer
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. np.smith@auckland.ac.nz.
authors.forename: Nic
authors.initials: N
authors.lastname: Smith
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK. s.ourselin@ucl.ac.uk.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Ourselin
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. aldo.rinaldi@gstt.nhs.uk.|The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK. aldo.rinaldi@gstt.nhs.uk.
authors.forename: Christopher Aldo
authors.initials: CA
authors.lastname: Rinaldi
authors.affiliation: Biomedical Image Analysis Group, Department of Computing, Imperial College London, London, UK. dr@doc.ic.ac.uk.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rueckert
authors.affiliation: The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK. gerald.carr-white@gstt.nhs.uk.
authors.forename: Gerald
authors.initials: G
authors.lastname: Carr-White
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK. reza.razavi@kcl.ac.uk.
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D058406:Cardiac Resynchronization Therapy; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D018579:Patient Selection; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling
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