Related Experiment Videos
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
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.
Abstract:
The poor sensitivity and the poor predictive value of ST-segment depression have limited the usefulness of the exercise electrocardiogram (ECG) in the diagnosis and evaluation of coronary artery disease (CAD). The QT dispersion (QTD), recorded as the difference between maximal and minimal QT intervals on a 12-lead exercise ECG, is sensitive to myocardial ischemia and may improve the accuracy of exercise testing in patients with CAD who do not show an ST-segment depression. Exercise ECGs were analyzed in 50 subjects who had undergone coronary angiography for clinical indications. None of them showed an ST-segment depression during or after exercise: There were 25 patients with significant coronary artery stenosis and 25 without significant stenosis. The QTD measured before, immediately after, and 1 min after exercise was similar in the 2 groups. The QTD at 3 and 5 min after exercise was significantly greater in patients with CAD than in the controls, and the most marked difference in QTD was observed at 3 min after exercise. A QTD at 3 min after exercise of >60 ms had a sensitivity of 80% and specificity of 88% regarding the diagnosis of CAD. When a deltaQTD (post-exercise QTD minus QTD at rest) at 3 min after exercise of >0 ms was added to a QTD of >60 ms as a condition for positivity, the specificity increased to 96%. QTD measured at 3 min after exercise increases the accuracy of exercise testing in patients with CAD who do not show an ST-segment depression.