title: Increased QT interval variability in 3 recently concussed athletes: an exploratory observation.
abstract: BACKGROUND
  The QT interval variability index (QTVI) is a noninvasive measure of beat-to-beat fluctuations of the QT interval as seen from a single electrocardiographic lead. It represents the relationship between the respective variabilities of the QT and R-R intervals. Recently, the QTVI was demonstrated to be an index of vagal cardiac autonomic modulation in resting conditions.
  
  
  OBJECTIVE
  To determine whether QTVI varied in athletes at 48 hours, 1 week, and 2 weeks after a concussive head injury.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Testing facility.
  
  
  METHODS
  Three athletes with recent concussions and 3 uninjured athletes with similar demographic factors.
  
  
  METHODS
  Continuous 3-lead electrocardiograms were obtained in a seated, resting position over 2 successive weeks. Separate, unpaired t tests were performed to determine whether group-visit differences were present in the QTVI at 48 hours, 1 week, or 2 weeks.
  
  
  RESULTS
  No demographic differences were present between groups. At 48 hours, the QTVI was greater in the concussion group than in the matched controls. At weeks 1 and 2, the QTVI in the concussion group was lower than at 48 hours and not different from that of the control group.
  
  
  CONCLUSIONS
  Vagal cardiac autonomic modulation, as quantified by the QTVI, appeared to be negatively affected in concussed athletes within 48 hours of injury, resolved within 1 week, and remained at control group levels 2 weeks later. Serial assessments of QTVI may be of clinical utility in identifying suspected cases of acute concussion and may provide helpful information for determining when an athlete can return to play safely.
authors.affiliation: Center of Excellence on the Medical Consequences of Spinal Cord Injury and SCI Service, James J. Peters VA Medical Center, Bronx, NY 10468, USA. michael.lafountaine@va.gov
authors.forename: Michael F
authors.initials: MF
authors.lastname: La Fountaine
authors.forename: James D
authors.initials: JD
authors.lastname: Gossett
authors.forename: Ronald E
authors.initials: RE
authors.lastname: De Meersman
authors.forename: William A
authors.initials: WA
authors.lastname: Bauman
mesh_terms: D000293:Adolescent; D056352:Athletes; D001341:Autonomic Nervous System / Q000503:physiopathology; D001924:Brain Concussion / Q000503:physiopathology*; D006259:Craniocerebral Trauma / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D055815:Young Adult