title: Patterns of Mechanical Inefficiency in Pediatric Dilated Cardiomyopathy and Their Relation to Left Ventricular Function and Clinical Outcomes.
abstract: BACKGROUND
  Pediatric dilated cardiomyopathy (DCM) is associated with death or transplantation and is typically considered a homogeneous process affecting global left ventricular (LV) function. However, assessment of regional abnormalities that contribute to pumping inefficiencies is lacking. The aim of this study was to define regional strain patterns of mechanical inefficiency in the broader context of LV discoordination (dysfunction and timing abnormalities) and to evaluate their associations with LV function and clinical outcomes.
  
  
  METHODS
  Multiplanar apical LV echocardiographic images from patients with pediatric DCM (n = 56) and control subjects (n = 20) were analyzed by two-dimensional longitudinal speckle-tracking strain analysis to identify segmental strain patterns and global contraction groups. Clinical outcome (death or transplantation vs transplantation-free survival) and echocardiographic data were evaluated. Outcome groups were compared using the Fisher exact test, the χ(2) test, or analysis of variance (with P values ≤ .05 considered to indicate statistical significance).
  
  
  RESULTS
  Of 56 patients with DCM, 29 (52%) progressed to death or transplantation. Five segmental strain patterns were observed that were used to define seven contraction groups by regional contractility and/or timing discoordination. The group(s) with the most discoordination had the most LV dysfunction (P = .0004) and a trend toward the highest frequency of death or transplantation (P = .069). Interreader reproducibility of segmental strain patterns agreed in 165 or 180 (92%) segments tested (κ = 0.90). Control subjects had normal strain patterns.
  
  
  CONCLUSIONS
  A heterogeneous mixture of abnormalities in the regional wall mechanics that lead to inefficient pump mechanics through functional and timing abnormalities were seen in this cohort and were categorized into natural subgroups. More severe LV discoordination was associated with increased LV dysfunction and a trend toward death or transplantation.
authors.affiliation: Division of Cardiology, Ward Family Heart Center, Children's Mercy Hospital, Kansas City, Missouri.
authors.forename: Daniel
authors.initials: D
authors.lastname: Forsha
authors.affiliation: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Cameron
authors.initials: C
authors.lastname: Slorach
authors.affiliation: Department of Paediatric Subspecialties, Cardiology Service, KK Women's and Children's Hospital, Singapore.
authors.forename: Ching Kit
authors.initials: CK
authors.lastname: Chen
authors.affiliation: Division of Cardiology, Ward Family Heart Center, Children's Mercy Hospital, Kansas City, Missouri.
authors.forename: Ashley
authors.initials: A
authors.lastname: Sherman
authors.affiliation: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
authors.affiliation: Division of Pediatric Cardiology, Duke University Medical Center, Durham, North Carolina.
authors.forename: Piers
authors.initials: P
authors.lastname: Barker
authors.affiliation: Cardiovascular Disease, Duke University Medical Center, Durham, North Carolina.
authors.forename: Joseph
authors.initials: J
authors.lastname: Kisslo
authors.affiliation: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: mark.friedberg@sickkids.ca.
authors.forename: Mark K
authors.initials: MK
authors.lastname: Friedberg
mesh_terms: D000293:Adolescent; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000401:mortality*; D015984:Causality; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D004452:Echocardiography / Q000706:statistics & numerical data*; D054459:Elasticity Imaging Techniques / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009864:Ontario / Q000453:epidemiology; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000401:mortality*
keywords: Dilated cardiomyopathy; Discoordination; Dyssynchrony; Pediatric; Strain pattern