title: Characterization of Myocardial Repolarization Reserve in Adolescent Females With Anorexia Nervosa.
abstract: BACKGROUND
  Patients with anorexia nervosa exhibit abnormal myocardial repolarization and are susceptible to sudden cardiac death. Exercise testing is useful in unmasking QT prolongation in disorders associated with abnormal repolarization. We characterized QT adaptation during exercise in anorexia.
  
  
  RESULTS
  Sixty-one adolescent female patients with anorexia nervosa and 45 age- and sex-matched healthy volunteers performed symptom-limited cycle ergometry during 12-lead ECG monitoring. Changes in the QT interval during exercise were measured, and QT/RR-interval slopes were determined by using mixed-effects regression modeling. Patients had significantly lower body mass index than controls; however, resting heart rates and QT/QTc intervals were similar at baseline. Patients had shorter exercise times (13.7±4.5 versus 20.6±4.5 minutes; P<0.001) and lower peak heart rates (159±20 versus 184±9 beats/min; P<0.001). The mean QTc intervals were longer at peak exercise in patients (442±29 versus 422±19 ms; P<0.001). During submaximal exertion at comparable heart rates (114±6 versus 115±11 beats/min; P=0.54), the QTc interval had prolonged significantly more in patients than controls (37±28 versus 24±25 ms; P<0.016). The RR/QT slope, best described by a curvilinear relationship, was more gradual in patients than in controls (13.4; 95% confidence interval, 12.8-13.9 versus 15.8; 95% confidence interval, 15.3-16.4 ms QT change per 10% change in RR interval; P<0.001) and steepest in patients within the highest body mass index tertile versus the lowest (13.9; 95% confidence interval, 12.9-14.9 versus 12.3; 95% confidence interval, 11.3-13.3; P=0.026).
  
  
  CONCLUSIONS
  Despite the absence of manifest QT prolongation, adolescent anorexic females have impaired repolarization reserve in comparison with healthy controls. Further study may identify impaired QT dynamics as a risk factor for arrhythmias in anorexia nervosa.
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Padfield
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Carolina A
authors.initials: CA
authors.lastname: Escudero
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Astrid M
authors.initials: AM
authors.lastname: DeSouza
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Christian
authors.initials: C
authors.lastname: Steinberg
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Karen
authors.initials: K
authors.lastname: Gibbs
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Puyat
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Pei Yoong
authors.initials: PY
authors.lastname: Lam
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Shubhayan
authors.initials: S
authors.lastname: Sanatani
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Sherwin
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: James E
authors.initials: JE
authors.lastname: Potts
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.).
authors.forename: George
authors.initials: G
authors.lastname: Sandor
authors.affiliation: From Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, Canada (G.J.P., C.S., K.G., A.D.K.); British Columbia Children's Hospital, Vancouver, Canada (C.A.E., A.M.D., P.Y.L., S.S., E.S., J.E.P., G.S.); and Centre for Health Evaluation and Outcome Sciences, University of British Columbia, Vancouver, Canada (J.H.P.). akrahn@mail.ubc.ca.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
mesh_terms: D000293:Adolescent; D000856:Anorexia Nervosa / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D053840:Brugada Syndrome / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D000075224:Cardiac Conduction System Disease; D002648:Child; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control; D004562:Electrocardiography / Q000379:methods; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D055815:Young Adult
keywords: QT interval; QT/RR slope; anorexia nervosa; exercise test; repolarization reserve