Related Experiment Videos
Precordial QT dispersion does not predict inducibility of ventricular tachyarrhythmias at post-revascularization
Satish R Raj1, L Brent Mitchell, D George Wyse
1Division of Cardiology, Foothills Medical Centre and the Cardiovascular Disease Research Group, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada, T2N 4N1.
Insights
Coronary artery revascularization reduced QT interval dispersion in patients with ventricular tachycardia. However, QT interval dispersion did not predict the outcome of electrophysiologic studies or patient survival.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Surgery
Background:
- QT interval dispersion may reflect inhomogeneous ventricular repolarization.
- Its predictive value for ventricular tachyarrhythmias (VT) post-revascularization is unclear.
Purpose of the Study:
- To determine if revascularization decreases QT interval dispersion.
- To assess if QT interval dispersion predicts electrophysiologic study outcomes after revascularization.
Main Methods:
- Measured QT interval dispersion before and after coronary artery revascularization.
- Assessed VT inducibility during electrophysiologic studies.
- Followed patients for 80 months for survival.
Main Results:
- Revascularization significantly decreased QT interval dispersion (69 to 53 ms).
- QT interval dispersion did not predict VT inducibility (p=0.2).
- Changes in dispersion also failed to predict VT inducibility (p=0.9).
Conclusions:
- Coronary artery revascularization effectively reduces QT interval dispersion.
- QT interval dispersion is not a reliable predictor of VT inducibility or long-term survival post-revascularization.
Objectives:
We tested the hypothesis that revascularization would decrease QT interval dispersion and that QT interval dispersion would predict the outcome of the electrophysiologic study following revascularization.
Background:
QT interval dispersion may be a measure of the inhomogeneity of ventricular repolarization. The value of the QT interval dispersion for predicting inducibility of ventricular tachyarrhythmias (VT) during electrophysiologic studies after coronary artery revascularization in patients with hemodynamically significant VT is unknown.
Methods And Results:
QT interval dispersions were measured from electrocardiograms recorded before and after coronary artery revascularization, but before an electrophysiologic study during the same hospitalization. Fifty-six patients (93% male, 65.1 +/- 9.6 years) were studied. QT interval dispersion decreased significantly following revascularization from 69 +/- 31 ms to 53 +/- 23 ms (p=0.002). Inducibility of VT could not be predicted by the QT interval dispersion following revascularization (50 +/- 30 ms in patients with VT induced vs. 58 +/- 25 ms in patients without VT induced at electrophysiologic study; p=0.2). The change in QT interval dispersion with revascularization (-15 +/- 33 ms vs. -17 +/- 46 ms; p=0.9) could not predict VT inducibility. Actuarial survival after 80 months follow-up was similar in the patients in whom VT was induced (82%) and those patients in whom VT was not induced (83%; p=NS).
Conclusions:
Coronary artery revascularization decreased QT interval dispersion in patients with hemodynamically significant VT, but QT interval dispersion was not predictive of inducibility of VT at follow-up electrophysiologic study. Actuarial survival was similar in patients in whom VT was induced and patients in whom VT was not induced.