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 language | English (US) |
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Pages (from-to) | 19-25 |
Number of pages | 7 |
Journal | Journal of Electrocardiology |
Volume | 35 |
Issue number | 1 |
DOIs | |
State | Published - 2002 |
Keywords
- Electrocardiography
- Heart rate variability
- Ischemia
- Myocardial repolarization
- QT interval
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine