Document Detail

Utility of the recovery electrocardiogram after exercise: a novel indicator for the diagnosis and genotyping of long QT syndrome?
MedLine Citation:
PMID:  20226272     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Exercise testing has shown modest utility in the ability to diagnose and genotype long QT syndrome (LQTS). Although numerous small studies have shown a genotype-specific repolarization response to exercise, the repolarization responses during recovery from exercise have received less focus.
OBJECTIVE: The purpose of this study was to characterize genotype-specific QT responses during recovery from exercise and to determine its potential as a diagnostic and genotyping tool.
METHODS: Seventy-five patients were age and sex matched into three groups (n = 25): LQT1, LQT2, and unaffected controls based on Schwartz score and genetic testing results. Each group underwent upright burst and gradual bicycle exercise testing while being monitored by 12-lead electrocardiogram.
RESULTS: LQT1 patients had significantly longer corrected QT (QTc) than LQT2 intervals during early recovery (P <.01). Control subjects showed little variation in QTc throughout the recovery period, maintaining a QTc within normal limits. Each group showed a distinct pattern of QTc adaptation during recovery. LQT1 patients began the recovery period at a QTc of 492 +/- 11 ms, after which the QTc decreased by 33 +/- 11 ms during recovery. Conversely, the LQT2 patients began recovery at its lowest mean QTc of 420 +/- 10 ms, which increased by 40 +/- 16 ms. At the end of recovery, a QTc cut-off value of 445 ms distinguished 92% of LQTS patients from unaffected controls, while a start-of-recovery QTc cut-off of 460 ms correctly identified genotype in 80% of LQT1 and 92% of LQT2 patients.
CONCLUSIONS: Genotype-specific differences exist in QT recovery after exercise. These differences can help to identify LQTS patients and distinguish LQT1 from LQT2 genotypes.
Ishvinder S Chattha; Raymond W Sy; Raymond Yee; Lorne J Gula; Allan C Skanes; George J Klein; Matthew T Bennett; Andrew D Krahn
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-03-10
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  7     ISSN:  1556-3871     ISO Abbreviation:  Heart Rhythm     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-07-15     Completed Date:  2010-11-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  United States    
Other Details:
Languages:  eng     Pagination:  906-11     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
Division of Cardiology, University of Western Ontario, London, Ontario, Canada.
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MeSH Terms
Adaptation, Physiological
Exercise / physiology*
Exercise Test
Long QT Syndrome / genetics*
Middle Aged
Young Adult

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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