title: High prevalence of repolarization abnormalities in children with simple ventricular ectopy.
abstract: BACKGROUND
  Premature ventricular contractions (PVCs) may occur in 0.3 to 2.2% of routine resting electrocardiograms (ECGs) in children with structurally normal hearts.
  
  
  OBJECTIVE
  This study tests the hypothesis that repolarization abnormalities are present more frequently on the surface ECG in pediatric patients with benign ventricular ectopy.
  
  
  METHODS
  A retrospective study was performed examining 32 children with benign ventricular ectopy and structurally normal hearts. The surface ECG was carefully reviewed, concentrating on repolarization abnormalities as evidenced by a prolonged QTc, a prolonged JTc, and/or an abnormal T-wave vector. QTc was calculated using Bazett's formula and considered prolonged if > 440 ms, and the JTc was calculated using a formula analogous to Bazett's formula and considered prolonged if > 340 ms. The T-wave vector was considered normal if between 0 to +90 degrees, concordant with the frontal QRS axis and within 60 degrees of the QRS axis. There were 13 females (41%) and 19 males (59%) with an average age of 9.1 years (range 1-16.1 years). These patients were then compared with age- and gender-matched controls. Fourteen of 32 study patients (44%) and 2 of 32 controls (6%) had evidence of repolarization abnormalities.
  
  
  RESULTS
  Using chi 2 analysis, there was a significant difference between groups (p = 0.0005). No patient had an abnormal T-wave vector and there were no other significant ECG abnormalities. There was no significant relationship between repolarization abnormalities and patient gender or age.
  
  
  CONCLUSIONS
  A significant percentage (44%; P = 0.0005) of children with benign ventricular ectopy have associated repolarization abnormalities as evidenced by a prolonged QTc and/or JTc. This finding suggests that children with "benign PVCs" may have repolarization changes indicative of underlying substrate abnormalities.
authors.affiliation: South Carolina Children's Heart Center, Medical University of South Carolina, Charleston 29425, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Miga
authors.forename: C L
authors.initials: CL
authors.lastname: Case
authors.forename: P C
authors.initials: PC
authors.lastname: Gillette
mesh_terms: D000293:Adolescent; D000367:Age Factors; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D012737:Sex Factors; D018879:Ventricular Premature Complexes / Q000175:diagnosis / Q000503:physiopathology*