title: Diagnostic value of T-wave morphology changes during "QT stretching" in patients with long QT syndrome.
abstract: BACKGROUND
  Specific T-wave patterns on the resting electrocardiogram (ECG) aid in diagnosing long QT syndrome (LQTS) and identifying the specific genotype. However, provocation tests often are required to establish a diagnosis when the QT interval is borderline at rest.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether T-wave morphology changes provoked by standing aid in the diagnosis of LQTS and determination of the genotype.
  
  
  METHODS
  The quick-standing test was performed by 100 LQTS patients (40 type 1 [LQT1], 42 type 2 [LQT2], 18 type 3 [LQT3]) and 100 controls. Logistic regression was used to determine whether T-wave morphology changes provoked by standing added to the already established diagnostic value of QTc stretching in identifying LQTS.
  
  
  RESULTS
  During maximal QT stretching, the T-wave morphologies that best discriminated LQTS from controls included "notched," "late-onset," and "biphasic" T waves. These 3 categories were grouped into a category named "abnormal T-wave response to standing." During quick standing, a QTc stretched ≥490 ms increased the odds of correctly identifying LQTS. T-wave morphology changes provoked by standing were most helpful for identifying LQT2, less helpful for LQT1, and least helpful for LQT3.
  
  
  CONCLUSIONS
  The sudden heart rate acceleration produced by abrupt standing not only increases the QTc but also exposes abnormal T waves that are valuable for diagnosing LQTS.
authors.affiliation: Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ehud
authors.initials: E
authors.lastname: Chorin
authors.affiliation: Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ofer
authors.initials: O
authors.lastname: Havakuk
authors.affiliation: Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Arnon
authors.initials: A
authors.lastname: Adler
authors.affiliation: Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Arie
authors.initials: A
authors.lastname: Steinvil
authors.affiliation: Department of Internal Medicine, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Uri
authors.initials: U
authors.lastname: Rozovski
authors.affiliation: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Christian
authors.initials: C
authors.lastname: van der Werf
authors.affiliation: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Pieter G
authors.initials: PG
authors.lastname: Postema
authors.affiliation: Department of Internal Medicine, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Topaz
authors.affiliation: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Arthur A M
authors.initials: AA
authors.lastname: Wilde
authors.affiliation: Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: samiviskin@gmail.com.
authors.forename: Sami
authors.initials: S
authors.lastname: Viskin
authors.affiliation: Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Raphael
authors.initials: R
authors.lastname: Rosso
mesh_terms: D000328:Adult; D053840:Brugada Syndrome / Q000175:diagnosis*; D000075224:Cardiac Conduction System Disease; D016022:Case-Control Studies; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005838:Genotype; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013610:Tachycardia / Q000175:diagnosis*; D055815:Young Adult
keywords: Electrocardiogram; Long QT syndrome; QT interval; T-wave morphology