Pediatric Cardiology

, Volume 24, Issue 6, pp 553–558 | Cite as

Effects of β-Adrenergic Antagonists on the QT Measurements from Exercise Stress Tests in Pediatric Patients with Long QT Syndrome

  • J. R. Kaltman
  • P. S. Ro
  • P. Stephens
  • M. G. McBride
  • M. I. Cohen
  • R. E. Tanel
  • V. L. Vetter
  • L. A. Rhodes
Article

Abstract

It has been proposed that β-adrenergic antagonist protection against cardiac events in patients with long QT syndrome (LQTS) may be related to a decrease in baseline QTc dispersion. To determine the effects of β-blocker therapy on QT measurements, we evaluated the exercise tests of 25 pediatric patients with LQTS. Measurements were made of the maximum QTc interval and QTc dispersion during the various segments of the exercise test. There was no statistically significant difference between the pre-β-blocker and post-β-blocker maximum QTc interval during the supine (0.473 ± 0.039 vs 0.470 ± 0.038 sec), exercise (0.488 ± 0.044 vs 0.500 ± 0.026 sec), or recovery (0.490 ± 0.031 vs 0.493 ± 0.029 sec) phases of the exercise stress test. There was also no statistically significant difference between the pre-β-blocker and post-β-blocker QTc dispersion during the supine (0.047 ± 0.021 vs 0.058 ± 0.033 sec), exercise (0.063 ± 0.036 vs 0.063 ± 0.028 sec), or recovery (0.045 ± 0.023 vs 0.052 ± 0.026 sec) phases of the exercise stress test. Therefore, the protection that β-blockers offer appears not to be related to a reduction of the baseline QTc interval or a decrease of QTc dispersion.

Keywords

Long QT syndrome QT dispersion β-Adrenergic antagonists 

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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • J. R. Kaltman
    • 1
  • P. S. Ro
    • 2
  • P. Stephens
    • 1
  • M. G. McBride
    • 1
  • M. I. Cohen
    • 3
  • R. E. Tanel
    • 1
  • V. L. Vetter
    • 1
  • L. A. Rhodes
    • 1
  1. 1.Department of PediatricsUniversity of Pennsylvania School of Medicine and the Cardiac Center at The Children’s Hospital of Philadelphia, 34th and Civic Center Boulevard, Philadelphia, PA 19103USA
  2. 2.Department of PediatricsThe Ohio State University School of Medicine, Columbus Children’s Hospital, 700 Children’s Drive, Columbus, OH 43205USA
  3. 3.Pediatric Cardiology Consultants, 333 East Virginia Avenue, Phoenix, AZ 85004USA

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