title: A comparison between radial strain evaluation by speckle-tracking echocardiography and cardiac magnetic resonance imaging, for assessment of suitable segments for left ventricular lead placement in cardiac resynchronization therapy.
abstract: OBJECTIVE
  A cut-off of 9.8% maximum speckle-tracking radial strain in the segment with the latest mechanical delay has been proposed as predictive for selecting the best left ventricular lead placement for positive response on cardiac resynchronization therapy (CRT). However, pacing transmural scar should be avoided, and the purpose of this study was to evaluate the ability of echocardiographic radial strain to predict the presence of scar in the left ventricle segments.
  
  
  RESULTS
  A total of 404 left ventricular segments were analysed, from 34 patients eligible for CRT. Pre-operative cardiac magnetic resonance (CMR) and echocardiography were performed, and maximal strain values from echocardiography speckle tracking were compared with CMR data. Hypokinesia and strain values showed a strong correlation (P < 0.001). Even though segments with CMR-verified scar had lower strain values than segments without scar (14.8 ± 7 vs. 16.0 ± 10), the predictive value of the proposed 9.8% cut-off was low (sensitivity 33% and specificity 72%). Scar burden was higher in ischaemic patients (13.5 vs. 5.3% P = 0.0001). Relative difference in strain values (target segment strain compared with the average strain value of the adjacent segments) was higher if there was transmural scar in the target segment as compared with a hypokinetic but viable target segment (87 vs. 38% difference, P = 0.03).
  
  
  CONCLUSIONS
  Speckle tracking radial strain should ideally be complemented by CMR for accurate assessment of viability, especially for patients with ischaemic aetiology of heart failure where transmural scar is more common. Comparison of strain values with the adjacent segments may be helpful for assessing viability.
authors.affiliation: Arrhythmia Clinic, Lund University, Skane University Hospital, Getingevagen 4, Lund 221 85, Sweden.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Bakos
authors.affiliation: Center för Medical Imaging and Physiology, Department of Clinical Physiology at Lund University and Skåne University Hospital, Lund 221 85, Sweden.
authors.forename: Ellen
authors.initials: E
authors.lastname: Ostenfeld
authors.affiliation: Center for Medical Imaging and Physiology, Lund University, Skane University Hospital, Getingevagen 4, Lund 221 85, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Markstad
authors.affiliation: The Clinic for Heart Failure and Valvular Disease, Lund University, Skane University Hospital, Getingevagen 4, Lund 221 85, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Werther-Evaldsson
authors.affiliation: The Clinic for Heart Failure and Valvular Disease, Lund University, Skane University Hospital, Getingevagen 4, Lund 221 85, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Roijer
authors.affiliation: Center för Medical Imaging and Physiology, Department of Clinical Physiology at Lund University and Skåne University Hospital, Lund 221 85, Sweden.
authors.forename: Hakan
authors.initials: H
authors.lastname: Arheden
authors.affiliation: Center för Medical Imaging and Physiology, Department of Clinical Physiology at Lund University and Skåne University Hospital, Lund 221 85, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Carlsson
authors.affiliation: Arrhythmia Clinic, Lund University, Skane University Hospital, Getingevagen 4, Lund 221 85, Sweden rasmus.borgquist@med.lu.se.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Borgquist
mesh_terms: D000368:Aged; D016880:Anisotropy; D058406:Cardiac Resynchronization Therapy / Q000379:methods; D058409:Cardiac Resynchronization Therapy Devices; D004452:Echocardiography / Q000379:methods*; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D004567:Electrodes, Implanted; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D019919:Prosthesis Implantation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013718:Tensile Strength
keywords: Cardiac magnetic resonance; Cardiac resynchronization therapy; Heart failure; Radial strain imaging; Speckle tracking