| Repolarization dynamics during exercise discriminate between LQT1 and LQT2 genotypes. | |
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MedLine Citation:
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PMID: 20455992 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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BACKGROUND: Repolarization dynamics during exercise in patients with long-QT Syndrome (LQTS) may be influenced by various factors such as a patient's genotype. We sought to systematically characterize the repolarization dynamics during exercise in patients with LQTS with a particular focus on the influence of genotype. METHODS: Three groups of patients were studied on the basis of clinical status and genotype: LQT1, LQT2, and normal controls. Twenty-five age- and gender-matched patients were selected for each group. The QTc was measured during bicycle exercise testing and its dynamics were compared between the 3 groups. RESULTS: The degree of QTc prolongation during exercise was greater in LQTS patients (LQT1 80 ± 47 ms, LQT2 64 ± 41 ms, Control 46 ± 20 ms, P = 0.02), with significant differences between LQT1 and LQT2 patients observed at heart rates ≥ 60% of the predicted maximum (P < 0.05). LQT1 patients demonstrated progressive or persistent QTc prolongation at higher heart rates, whereas LQT2 patients demonstrated maximum QTc prolongation at submaximal heart rates (50% of the predicted maximum) with subsequent QTc correction toward baseline values at higher heart rates. Importantly, these observations were consistent regardless of age, gender, or exercise type in subgroup analyses. CONCLUSIONS: Reduced repolarization reserve in LQTS is genotype and heart rate specific. |
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Authors:
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Raymond W Sy; Ishvinder S Chattha; George J Klein; Lorne J Gula; Allan C Skanes; Raymond Yee; Matthew T Bennett; Andrew D Krahn |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of cardiovascular electrophysiology Volume: 21 ISSN: 1540-8167 ISO Abbreviation: J. Cardiovasc. Electrophysiol. Publication Date: 2010 Nov |
Date Detail:
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Created Date: 2010-11-02 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9010756 Medline TA: J Cardiovasc Electrophysiol Country: United States |
Other Details:
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Languages: eng Pagination: 1242-6 Citation Subset: IM |
Copyright Information:
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© 2010 Wiley Periodicals, Inc. |
Affiliation:
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Division of Cardiology, University of Western Ontario, London, Ontario, Canada. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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