Beat-to-beat QT interval variability associated with acute myocardial ischemia

Taizo Murabayashi, Barry Fetics, David Kass, Erez Nevo, Boris Gramatikov, Ronald D. Berger

Research output: Contribution to journalArticlepeer-review

Abstract

Beat-to-beat QT interval variability (QTV) quantifies lability in ventricular repolarization. We hypothesized that myocardial ischemia destabilizes ventricular repolarization and increases QTV. We analyzed 2-hour 2-lead digitized electrocardiogram records of 68 patients in the European ST-T Database. All patients had ischemic episodes during the 2-hour record, annotated by the developers of the database. We determined the normalized QTV (QTVnorm), QT variability index (QTVI), and normalized heart rate variability (HRVnorm) for each 5-minute epoch by automated analysis. QTVnorm was greater during ischemic episodes than during nonischemic episodes (1.41 ± 0.77 vs. 0.88 ± 0.23, P < .0001). There was no significant difference in HRVnorm between ischemic and nonischemic episodes (1.22 ± 0.63 vs. 0.94 ± 0.18, not significant). The QTVI was higher during ischemic episodes than during nonischemic episodes (0.14 ± 0.31 vs. -0.051 ± 0.12, P < .0001). Acute ischemia is associated with labile ventricular repolarization, which manifests as enhanced beat-to-beat QT interval variability. The association between ischemic repolarization liability and arrhythmic risk deserves further study.

Original languageEnglish (US)
Pages (from-to)19-25
Number of pages7
JournalJournal of Electrocardiology
Volume35
Issue number1
DOIs
StatePublished - 2002

Keywords

  • Electrocardiography
  • Heart rate variability
  • Ischemia
  • Myocardial repolarization
  • QT interval

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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