title: Classic-pattern dyssynchrony and electrical activation delays in pediatric dilated cardiomyopathy.
abstract: BACKGROUND
  Progressive heart failure leading to transplantation or death is common in pediatric dilated cardiomyopathy (DCM), and treatment options are limited. Select children with DCM have improved after cardiac resynchronization therapy (CRT), but predicting response is challenging. Nonetheless, considering the frequency of death or transplantation in this population, identifying any candidate would be valuable. Classic-pattern dyssynchrony (CPD) identifies mechanical dyssynchrony patterns consistent with underlying electrical activation delays and strongly predicts CRT response in adult DCM but has not been evaluated in pediatric DCM. The aim of this study was to test the hypothesis that CPD is present in a subgroup of patients with pediatric DCM and is associated with activation delays.
  
  
  METHODS
  Fifty-nine subjects with pediatric DCM (left ventricular end-diastolic diameter Z score > 2 and left ventricular ejection fraction < 40%) who underwent echocardiography with a functional protocol with apical images optimized for two-dimensional speckle-tracking strain analysis (EchoPAC) were retrospectively analyzed for CPD. Electrocardiograms were evaluated for activation delays (prolonged QRS duration and strict criteria for left bundle branch block [LBBB]). Forty control subjects with no cardiac disease and good imaging widows were also analyzed.
  
  
  RESULTS
  The mean age was 5.4 years (range, 1 day to 20 years); idiopathic DCM was most common (57%). Severe cardiomyopathy was present in 75% (end-diastolic diameter Z score > 4.6 and left ventricular ejection fraction < 32%). CPD was identified in seven subjects (12%), and prolonged QRS durations were present in 13 (22%), but only two subjects met strict criteria for LBBB. Six of seven subjects in the CPD group had prolonged QRS durations, and two of seven had LBBB. No control subjects had CPD. The CPD analysis was highly feasible and reproducible.
  
  
  CONCLUSIONS
  In this severely affected cohort, the small CPD subgroup is potentially important because their progressive disease may respond to CRT. CPD is associated with activation delays, although not necessarily strict LBBB. This has important potential implications for prospective evaluation of CRT in this disease.
authors: Division of Pediatric Cardiology, Duke University Medical Center, Durham, North Carolina.
authors: Daniel
authors: D
authors: Forsha
authors: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada.
authors: Cameron
authors: C
authors: Slorach
authors: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada.
authors: Ching Kit
authors: CK
authors: Chen
authors: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada.
authors: Elizabeth A
authors: EA
authors: Stephenson
authors: Department of Cardiology, Hvidorve Hospital, Copenhagen, Denmark.
authors: Niels
authors: N
authors: Risum
authors: Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina.
authors: Christoph
authors: C
authors: Hornik
authors: Division of Cardiovascular Disease, Duke University Medical Center, Durham, North Carolina.
authors: Galen
authors: G
authors: Wagner
authors: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada.
authors: Luc
authors: L
authors: Mertens
authors: Division of Pediatric Cardiology, Duke University Medical Center, Durham, North Carolina.
authors: Piers
authors: P
authors: Barker
authors: Division of Cardiovascular Disease, Duke University Medical Center, Durham, North Carolina.
authors: Joseph
authors: J
authors: Kisslo
authors: Department of Cardiology, Labatt Family Heart Centre, Toronto Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: mark.friedberg@sickkids.ca.
authors: Mark K
authors: MK
authors: Friedberg
mesh_terms: D000293:Adolescent; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging* / Q000209:etiology*; D002311:Cardiomyopathy, Dilated / Q000150:complications* / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004452:Echocardiography / Q000379:methods; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology*; D055815:Young Adult
keywords: Cardiac resynchronization therapy; Dilated cardiomyopathy; Dyssynchrony; Pediatric; Strain