Document Detail

The phenomenon of "QT stunning": the abnormal QT prolongation provoked by standing persists even as the heart rate returns to normal in patients with long QT syndrome.
MedLine Citation:
PMID:  22300664     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Patients with long QT syndrome (LQTS) have inadequate shortening of the QT interval in response to the sudden heart rate accelerations provoked by standing-a phenomenon of diagnostic value. We now validate our original observations in a cohort twice as large. We also describe that this abnormal QT-interval response persists as the heart rate acceleration returns to baseline.
OBJECTIVES: To describe a novel observation, termed "QT stunning" and to validate previous observations regarding the "QT-stretching" phenomenon in patients with LQTS by using our recently described "standing test."
METHODS: The electrocardiograms of 108 patients with LQTS and 112 healthy subjects were recorded in the supine position. Subjects were then instructed to stand up quickly and remain standing for 5 minutes during continuous electrocardiographic recording. The corrected QT interval was measured at baseline (QTc(base)), when heart rate acceleration without appropriate QT-interval shortening leads to maximal QT stretching (QTc(stretch)) and upon return of heart rate to baseline (QTc(return)).
RESULTS: QTc(stretch) lengthened significantly more in patients with LQTS (103 ± 80 ms vs 66 ± 40 ms in controls; P <.001) and so did QTc(return) (28 ± 48 ms for patients with LQTS vs -3 ± 32 ms for controls; P <.001). Using a sensitivity cutoff of 90%, the specificity for diagnosing LQTS was 74% for QTc(base), 84% for QTc(return), and 87% for QTc(stretch).
CONCLUSIONS: The present study extends our previous findings on the abnormal response of the QT interval in response to standing in patients with LQTS. Our study also shows that this abnormal response persists even after the heart rate slows back to baseline.
Arnon Adler; Christian van der Werf; Pieter G Postema; Raphael Rosso; Zahir A Bhuiyan; Jonathan M Kalman; Jitendra K Vohra; Milton E Guevara-Valdivia; Manlio F Marquez; Amir Halkin; Jesaia Benhorin; Charles Antzelevitch; Arthur A M Wilde; Sami Viskin
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2012-01-31
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  9     ISSN:  1556-3871     ISO Abbreviation:  Heart Rhythm     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-05-22     Completed Date:  2013-02-18     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  United States    
Other Details:
Languages:  eng     Pagination:  901-8     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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MeSH Terms
Exercise Test
Follow-Up Studies
Heart Conduction System / physiopathology*
Heart Rate / physiology*
Long QT Syndrome / diagnosis,  physiopathology*
ROC Curve
Recovery of Function / physiology*
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