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Published on: April 5, 2011

Changes of QT dispersion in patients with coronary artery disease dependent on different methods of stress induction

B Hailer1, P Van Leeuwen, D Sallner

  • 1Department of Medicine, Philippusstift, Essen, Germany.

Clinical Cardiology
|April 13, 2000
PubMed

Insights

Stress-induced increases in QT dispersion (QTd) can identify coronary artery disease (CAD). Pharmacologic stress, particularly with arbutamine, showed greater differences in QTd compared to exercise, suggesting a lower ischemic threshold.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Diagnostic Imaging

Background:

  • Stress-induced myocardial ischemia in coronary artery disease (CAD) patients can elevate QT dispersion (QTd).
  • QTd is a measure of repolarization variability on an electrocardiogram (ECG).

Purpose of the Study:

  • To investigate the impact of increasing heart rates on QTd.
  • To compare different stress induction methods for estimating QTd in CAD patients with varying disease severity.

Main Methods:

  • 58 patients underwent ECGs at rest, during dynamic exercise, and pharmacologic stress (arbutamine).
  • QTd was calculated by subtracting the minimal from the maximal QT interval duration at each stress level.
  • Echocardiography was used simultaneously with stress testing.

Main Results:

  • QTd was significantly higher in CAD patients at maximal heart rate, with pharmacologic stress yielding better group discrimination (p < 0.0001 for arbutamine).
  • Patients with prior myocardial infarction (MI) exhibited higher QTd values under all conditions.
  • Pharmacologic stress induced more radical QTd changes in CAD patients compared to dynamic exercise.

Conclusions:

  • QTd under stress effectively identifies patients with CAD.
  • Pharmacologic stress, especially with arbutamine, is more sensitive than dynamic exercise in revealing QTd abnormalities.
  • Elevated resting QTd in post-MI patients may mask stress-induced changes, indicating a potentially lower ischemic threshold.
Abstract

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