title: Comparison of formulas for calculation of the corrected QT interval in infants and young children.
abstract: OBJECTIVE
  To compare 4 heart rate correction formulas for calculation of the rate corrected QT (QTc) interval among infants and young children.
  
  
  METHODS
  R-R and QT intervals were measured from digital electrocardiograms. QTc were calculated with the Bazett, Fridericia, Hodges, and Framingham formulas. QTc vs R-R graphs were plotted, and slopes of the regression lines compared. Slopes of QTc-R-R regression lines close to zero indicate consistent QT corrections over the range of heart rates.
  
  
  RESULTS
  We reviewed electrocardiograms from 702 children, with 233 (33%) <1 year of age and 567 (81%) <2 years. The average heart rate was 122 ± 20 bpm (median 121 bpm). The slopes of the QTc-R-R regression lines for the 4 correction formulas were -0.019 (Bazett); 0.1028 (Fridericia); -0.1241 (Hodges); and 0.2748 (Framingham). With the Bazett formula, a QTc >460 ms was 2 SDs above the mean, compared with "prolonged" QTc values of 414, 443, and 353 ms for the Fridericia, Hodges, and Framingham formulas, respectively.
  
  
  CONCLUSIONS
  The Bazett formula calculated the most consistent QTc; 460 ms is the best threshold for prolonged QTc. The study supports continued use of the Bazett formula for infants and children and differs from the use of the Fridericia correction during clinical trials of new medications.
authors: Division of Pediatric Cardiology, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center, Torrance, CA.
authors: Derek Q
authors: DQ
authors: Phan
authors: Division of Cardiology, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA.
authors: Michael J
authors: MJ
authors: Silka
authors: Division of Pediatric Cardiology, Santa Clara Valley Medical Center, San Jose, CA.
authors: Yueh-Tze
authors: YT
authors: Lan
authors: Division of Pediatric Cardiology, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center, Torrance, CA. Electronic address: rkchang@ucla.edu.
authors: Ruey-Kang R
authors: RK
authors: Chang
mesh_terms: D000465:Algorithms; D002675:Child, Preschool; D004562:Electrocardiography / Q000706:statistics & numerical data*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D012849:Sinoatrial Node / Q000503:physiopathology
references: Heart. 2001 Aug;86(2):199-202
references: 11454842
references: Am J Cardiol. 1984 Jul 1;54(1):103-8
references: 6741799
references: Am Heart J. 1985 Feb;109(2):399-411
references: 3966369
references: J Pharmacol Methods. 1989 Nov;22(3):207-17
references: 2586115
references: Am J Cardiol. 1992 Sep 15;70(7):797-801
references: 1519533
references: Circulation. 1993 Aug;88(2):782-4
references: 8339437
references: Am J Cardiol. 1993 Aug 26;72(6):17B-22B
references: 8256750
references: Am J Cardiol. 1996 Oct 15;78(8):920-6
references: 8888666
references: N Engl J Med. 1998 Jun 11;338(24):1709-14
references: 9624190
references: Pacing Clin Electrophysiol. 1999 Sep;22(9):1397-401
references: 10527023
references: J Electrocardiol. 2004;37 Suppl:81-90
references: 15534815
references: J Cardiovasc Electrophysiol. 2005 Jan;16(1):76-81
references: 15673393
references: J Intern Med. 2006 Jan;259(1):39-47
references: 16336512
references: J Cardiovasc Electrophysiol. 2010 Aug 1;21(8):905-13
references: 20233271
references: Circulation. 2011 Nov 15;124(20):2181-4
references: 22083145
references: J Electrocardiol. 2012 May-Jun;45(3):288-93
references: 22361012
references: Circ Arrhythm Electrophysiol. 2013 Oct;6(5):932-8
references: 24036083
references: Am J Cardiol. 2013 Nov 1;112(9):1379-83
references: 23972343
references: J Pediatr. 2014 Mar;164(3):590-5.e1-3
references: 24388587
references: Heart Rhythm. 2014 Dec;11(12):2316-21
references: 25239430
references: Heart Rhythm. 2014 Dec;11(12):2322-7
references: 25239431
references: Heart Rhythm. 2006 Sep;3(9):1003-7
references: 16945790
references: Heart Rhythm. 2006 Nov;3(11):1353-5
references: 17074644
references: Heart Rhythm. 2006 Nov;3(11):1356-9
references: 17074645
references: Circulation. 2007 Jan 23;115(3):361-7
references: 17210839
references: J Am Coll Cardiol. 2009 Mar 17;53(11):982-91
references: 19281931
references: Circulation. 2009 Nov 3;120(18):1761-7
references: 19841298
references: J Electrocardiol. 2010 Jan-Feb;43(1):4-7
references: 19665725