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Significance of exercise QT dispersion in patients with coronary artery disease who do not have exercise-induced

M Yoshimura1, K Matsumoto, M Watanabe

  • 1Department of Cardiology, Saiseikai Hiroshima Hospital, Hiroshima, Japan. myoshimu@pop11.odn.ne.jp

Japanese Circulation Journal
|August 26, 1999
PubMed

Insights

QT dispersion (QTD) measured 3 minutes post-exercise improves coronary artery disease (CAD) diagnosis in patients lacking ST-segment depression. This method enhances exercise electrocardiogram (ECG) accuracy for detecting significant coronary stenosis.

Area of Science:

  • Cardiology
  • Diagnostic Imaging
  • Exercise Physiology

Background:

  • ST-segment depression on exercise electrocardiograms (ECGs) has limited diagnostic value for coronary artery disease (CAD).
  • Myocardial ischemia detection can be improved by novel ECG parameters beyond ST-segment analysis.

Purpose of the Study:

  • To evaluate the diagnostic utility of QT dispersion (QTD) during exercise testing in patients with suspected CAD.
  • To determine if QTD can enhance the accuracy of exercise ECGs in individuals without ST-segment depression.

Main Methods:

  • Analysis of 12-lead exercise ECGs in 50 subjects undergoing coronary angiography.
  • Measurement of QTD at rest, immediately, 1, 3, and 5 minutes post-exercise.
  • Comparison of QTD between 25 patients with significant coronary stenosis and 25 controls without stenosis.

Main Results:

  • QTD was similar between groups at rest and early post-exercise.
  • Significantly greater QTD was observed in CAD patients at 3 and 5 minutes post-exercise, peaking at 3 minutes.
  • A QTD >60 ms at 3 minutes post-exercise showed 80% sensitivity and 88% specificity for CAD.
  • Adding deltaQTD >0 ms at 3 minutes post-exercise increased specificity to 96%.

Conclusions:

  • QT dispersion measured 3 minutes post-exercise is a sensitive and specific indicator for diagnosing CAD in patients with non-diagnostic ST-segment depression.
  • This QTD measurement significantly improves the accuracy of exercise testing for CAD detection.

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