Long QT syndrome complicating atrioventricular block: Arrhythmogenic effects of cardiac memory

Raphael Rosso, Arnon Adler, Boris Strasberg, Milton E. Guevara-Valdivia, Riyaz Somani, Adrian Baranchuk, Amir Halkin, Manlio F. Márquez, Melvin Scheinman, Arie Steinvil, Bernard Belhassen, Mark Kazatsker, Amos Katz, Sami Viskin

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Background: The magnitude of QT prolongation in response to bradycardia, rather than the bradycardia per se, determines the risk for torsade de pointes during atrioventricular block (AVB). However, we do not know why some patients develop more QT prolongation than others, despite similar bradycardia. We hypothesized that in patients who develop significant QRS vector changes during AVB, the effects of cardiac memory lead to excessive QT prolongation. Methods and Results: We studied 91 patients who presented with AVB and who also had an ECG predating the bradyarrhythmia for comparison. We correlated changes in QRS morphology and axis taking place during AVB with the bradycardia-induced QT prolongation. Patients with and without QRS morphology changes at the time of AVB were of similar age and sex. Moreover, despite similar R-R interval during AVB, cases with a QRS morphology change had significantly longer QT (648±84 versus 561±84; P<0.001) than those without. Patients who developed a change in QRS morphology at the time of AVB had a 7-fold higher risk of developing long QT. This risk nearly doubled when the change in QRS morphology was accompanied by a change in QRS axis. Conclusions: Cardiac memory resulting from a change in QRS morphology during AVB is independently associated with QT prolongation and may be arrhythmogenic during AVB.

Original languageEnglish
Pages (from-to)1129-1135
Number of pages7
JournalCirculation: Arrhythmia and Electrophysiology
Volume7
Issue number6
DOIs
StatePublished - 1 Dec 2014

Keywords

  • Atrioventricular block
  • Long QT syndrome
  • Torsade de pointes

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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