title: The QT Scale: A Weight Scale Measuring the QTc Interval.
abstract: BACKGROUND
  Despite the strong evidence of the clinical utility of QTc prolongation as a surrogate marker of cardiac risk, QTc measurement is not part of clinical routine either in hospital or in physician offices. We evaluated a novel device ("the QT scale") to measure heart rate (HR) and QTc interval.
  
  
  METHODS
  The QT scale is a weight scale embedding an ECG acquisition system with four limb sensors (feet and hands: lead I, II, and III). We evaluated the reliability of QT scale in healthy subjects (cohort 1) and cardiac patients (cohorts 2 and 3) considering a learning (cohort 2) and two validation cohorts. The QT scale and the standard 12-lead recorder were compared using intraclass correlation coefficient (ICC) in cohorts 2 and 3. Absolute value of heart rate and QTc intervals between manual and automatic measurements using ECGs from the QT scale and a clinical device were compared in cohort 1.
  
  
  RESULTS
  We enrolled 16 subjects in cohort 1 (8 w, 8 m; 32 ± 8 vs 34 ± 10 years, P = 0.7), 51 patients in cohort 2 (13 w, 38 m; 61 ± 16 vs 58 ± 18 years, P = 0.6), and 13 AF patients in cohort 3 (4 w, 9 m; 63 ± 10 vs 64 ± 10 years, P = 0.9). Similar automatic heart rate and QTc were delivered by the scale and the clinical device in cohort 1: paired difference in RR and QTc were -7 ± 34 milliseconds (P = 0.37) and 3.4 ± 28.6 milliseconds (P = 0.64), respectively. The measurement of stability was slightly lower in ECG from the QT scale than from the clinical device (ICC: 91% vs 80%) in cohort 3.
  
  
  CONCLUSIONS
  The "QT scale device" delivers valid heart rate and QTc interval measurements.
authors.affiliation: Heart Research Follow-Up Program, Cardiology Department, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Couderc
authors.affiliation: Heart Research Follow-Up Program, Cardiology Department, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Connor
authors.initials: C
authors.lastname: Beshaw
authors.affiliation: Heart Research Follow-Up Program, Cardiology Department, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Niu
authors.affiliation: Universitat Politècnica de Catalunya, BarcelonaTech, Barcelona, Spain.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Serrano-Finetti
authors.affiliation: Universitat Politècnica de Catalunya, BarcelonaTech, Barcelona, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Casas
authors.affiliation: Universitat Politècnica de Catalunya, BarcelonaTech, Barcelona, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Pallas-Areny
authors.affiliation: Heart Research Follow-Up Program, Cardiology Department, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Spencer
authors.initials: S
authors.lastname: Rosero
authors.affiliation: Heart Research Follow-Up Program, Cardiology Department, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
mesh_terms: D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008133:Long QT Syndrome / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010627:Phenethylamines / Q000627:therapeutic use; D013449:Sulfonamides / Q000627:therapeutic use
chemical_list: D000889:Anti-Arrhythmia Agents; D010627:Phenethylamines; D013449:Sulfonamides; C063533:dofetilide
keywords: clinical; electrocardiography; electrophysiology; long QT syndrome; noninvasive techniques