Document Detail

Diagnostic performance of various QTc interval formulas in a large family with long QT syndrome type 3: Bazett's formula not so bad after all...
MedLine Citation:
PMID:  14516281     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Recently, we identified a novel mutation of SCN5A (1795insD) in a large family with LQTS3. The aim of this study was to assess whether the various proposed corrections of the QT interval to heart rate help to improve the identification of carriers of the mutant gene. METHODS: The study group consisted of 101 adult family members: 57 carriers and 44 noncarriers (mean age 44.6 +/- 14.6 and 40.3 +/- 12.8 years, respectively). In all individuals a 12-lead ECG, exercise ECG, and 24-hour Holter ECG were obtained. RESULTS: Correction for heart rate significantly improved the diagnostic performance of the QT interval. Diagnostic performance of the Bazett formula was similar to that of the newer formulas (Fridericia, Hodges, Framingham, and a logarithmic formula). At a cut-off value of 440 ms, the Bazett corrected QT interval was associated with a sensitivity and specificity of 90% and 91%, respectively. Using the 24-hour Holter ECG, a prolonged QTc at heart rates less than 60 beats/min was almost pathognomonic for genetic mutation (sensitivity and specificity both 99%), whereas the QTc calculated at the lowest heart rate using Bazett's formula provided full discrimination. CONCLUSION: In the present family, the resting ECG gave a good indication about the presence or absence of genetic mutation but a 24-hour Holter recording was mandatory to ascertain the diagnosis. In the diagnosis of this form of LQTS3, Bazett's formula was at least as good as other proposed corrections of the QT interval to heart rate.
Jan Brouwer; Maarten P Van Den Berg; Diederick E Grobbee; Jaap Haaksma; Arthur A M Wilde
Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc     Volume:  8     ISSN:  1082-720X     ISO Abbreviation:  Ann Noninvasive Electrocardiol     Publication Date:  2003 Oct 
Date Detail:
Created Date:  2003-09-30     Completed Date:  2004-02-27     Revised Date:  2008-03-10    
Medline Journal Info:
Nlm Unique ID:  9607443     Medline TA:  Ann Noninvasive Electrocardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  269-74     Citation Subset:  IM    
Department of Cardiology, Thorax Center, University Hospital Groningen, Groningen, The Netherlands.
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MeSH Terms
Case-Control Studies
Cohort Studies
Electrocardiography, Ambulatory
Exercise Test
Heart Rate / physiology
Long QT Syndrome / diagnosis*,  genetics*
Middle Aged
ROC Curve
Reference Values
Sensitivity and Specificity
Severity of Illness Index
Comment In:
Ann Noninvasive Electrocardiol. 2003 Oct;8(4):267-8   [PMID:  14516280 ]

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