Document Detail

Abnormal repolarization dynamics revealed in exercise test in long QT syndrome mutation carriers with normal resting QT interval.
MedLine Citation:
PMID:  20566482     Owner:  NLM     Status:  MEDLINE    
AIMS: The identification of affected family members with long QT syndrome (LQTS) is often difficult due to their normal-or only marginally lengthened-QT interval duration. We examined whether physical exercise test could increase the ability to detect the mutation carrier status in phenotypically normal LQTS family members.
METHODS AND RESULTS: Sixty-six subjects were included: 15 were carriers of KCNQ1 (LQT1); 15 of KCNH(2) (LQT2); and 9 of SCN5A (LQT3) gene mutations with no, or borderline, QT lengthening; and 27 were healthy controls. Multiple electrograms over the precordial area were recorded during workload and recovery phases of exercise test. QT intervals and T peak to T end intervals (Tpe intervals) were determined using an automatic algorithm at specified heart rates (HR).The LQT1 mutation carriers had QT interval most prolonged during exercise and recovery, whereas the LQT2 carriers had QT interval longest at low exercise HR. The LQT3 carriers had QT interval longest at rest. The Tpe interval remained nearly unchanged during exercise in LQT1, but shortened in LQT2 and in LQT3 carriers. The Tpe interval was longest in LQT2 carriers at the end of the recovery phase. Tentative dichotomizing values of QT and Tpe intervals improved sensitivity and specificity in distinguishing LQTS subtypes, compared with the QT interval duration alone.
CONCLUSIONS: LQTS mutation carriers lacking diagnostic QT interval prolongation exhibit abnormal QT and Tpe interval adaptations during physical exercise test. Looking for subtype-specific adaptations might facilitate the identification of LQTS mutation carriers when molecular genetic analysis is not available.
Anna-Mari Hekkala; Matti Viitasalo; Heikki Väänänen; Heikki Swan; Lauri Toivonen
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-06-20
Journal Detail:
Title:  Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology     Volume:  12     ISSN:  1532-2092     ISO Abbreviation:  Europace     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-08-25     Completed Date:  2011-01-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100883649     Medline TA:  Europace     Country:  England    
Other Details:
Languages:  eng     Pagination:  1296-301     Citation Subset:  IM    
Department of Cardiology, Helsinki University Hospital, Helsinki, Finland.
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MeSH Terms
Exercise Test
Heart Conduction System / physiopathology*
Long QT Syndrome / genetics*,  physiopathology*
Young Adult

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

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