title: Heritability of Tpeak-Tend interval and T-wave amplitude: a twin study.
abstract: BACKGROUND
  Tpeak-Tend interval (TpTe) and T-wave amplitude (Tamp) carry diagnostic and prognostic information regarding cardiac morbidity and mortality. Heart rate and QT interval are known to be heritable traits. The heritability of T-wave morphology parameters such as TpTe and Tamp is unknown. TpTe and Tamp were evaluated in a large sample of twins.
  
  
  RESULTS
  Twins from the GEMINAKAR study (611 pairs, 246 monozygotic, 365 dizygotic; mean age, 38±11 years; 49% men) who had an ECG performed during 1997 to 2000 were included. Tamp was measured in leads V1 and V5. Duration variables (RR interval, QTpeak and QTend interval) were measured and averaged over 3 consecutive beats in lead V5. TpTe was calculated as the QTend- and QTpeak-interval difference. Heritability was assessed using structural equation models adjusting for age, sex, and body mass index. All models were reducible to a model of additive genetics and unique environment. All variables had considerable genetic components. Adjusted heritability estimates were as follows: TpTe, 46%; Tamp lead V1, 34%; Tamp lead V5, 47%; RR interval, 55%; QT interval, 67%; and Bazett-corrected QT interval, 42%.
  
  
  CONCLUSIONS
  RR interval, QT interval, Tamp, and TpTe interval are heritable ECG parameters.
authors.affiliation: Laboratory of Experimental Cardiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Haarmark
authors.forename: Kirsten O
authors.initials: KO
authors.lastname: Kyvik
authors.forename: Esben
authors.initials: E
authors.lastname: Vedel-Larsen
authors.forename: Esben
authors.initials: E
authors.lastname: Budtz-Jørgensen
authors.forename: Jørgen K
authors.initials: JK
authors.lastname: Kanters
mesh_terms: D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000235:genetics*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019655:Quantitative Trait, Heritable; D012737:Sex Factors; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D016276:Ventricular Function / Q000235:genetics*