title: Reproducibility and diagnostic accuracy of three-layer speckle tracking echocardiography in a swine chronic ischemia model.
abstract: BACKGROUND
  The subendocardial myocardium normally has higher systolic strain than the subepicardial myocardium and can be damaged first in face of ischemia. We investigated the reproducibility and feasibility of novel three-layer speckle tracking system and compared the diagnostic accuracy with experienced visual interpretation.
  
  
  METHODS
  An ameroid constrictor was placed around the proximal left circumflex (LCX) coronary artery in 19 pigs. Four weeks later, subtotal stenosis was confirmed in all pigs by coronary angiogram. Two dead pigs and three pigs with pathological infarction were excluded. Transthoracic left ventricle (LV) short-axis echocardiograms were recorded at rest before and 4 weeks after the operation. LV posterior wall motion was scored by two experienced doctors and analyzed by the speckle tracking system (n = 14).
  
  
  RESULTS
  Strain variables gave reasonable intra/interobserver reproducibility (mean absolute percentage errors = 13/19, intraclass correlation coefficients = 0.97/0.92). All strain variables and visual wall-motion scores changed significantly during stenosis (P < 0.05). Of all variables, endocardial strains, particularly the circumferential strain demonstrated the highest area under curve (AUC), showing better diagnostic accuracy than experienced visual interpretation (sensitivity 0.93 vs. 0.79, specificity 0.93 vs. 0.73, AUC 0.95 vs. 0.77, P < 0.05).
  
  
  CONCLUSIONS
  Three-layer speckle tracking is a feasible and reproducible modality. In particular, endocardial speckle tracking provides incremental value in accurately identifying regional ischemia even in the rest echocardiography.
authors.affiliation: Department of Cardiovascular Medicine, The University of Tokyo, Tokyo, Japan. kimurak-int@h.u-tokyo.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Kimura
authors.forename: Katsu
authors.initials: K
authors.lastname: Takenaka
authors.forename: Aya
authors.initials: A
authors.lastname: Ebihara
authors.forename: Kansei
authors.initials: K
authors.lastname: Uno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwata
authors.forename: Masataka
authors.initials: M
authors.lastname: Sata
authors.forename: Takahide
authors.initials: T
authors.lastname: Kohro
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Morita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yatomi
authors.forename: Ryozo
authors.initials: R
authors.lastname: Nagai
mesh_terms: D000465:Algorithms; D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine