title: New parameters in the interpretation of exercise testing in women: QTc dispersion and QT dispersion ratio difference.
abstract: BACKGROUND
  It has been reported that the increase of QT dispersion (QTD) that occurs due to increased inhomogeneity of the ventricular repolarization because of transient ischemia obtained by standard 12-lead electrocardiogram (ECG), the changes during exercise, and the differences between exercise and rest increase the accuracy of exercise test in the diagnosis of coronary artery disease (CAD).
  
  
  OBJECTIVE
  This study was designed to investigate the value of QTD parameters, which are reported to increase the diagnostic accuracy of exercise test in women.
  
  
  METHODS
  Ninety-seven women who had undergone coronary angiography and exercise test were evaluated for diagnosis of chest pain. QT dispersion was calculated using the measurements of the highest and lowest values of QT interval obtained by ECG during peak exercise. The QTc using Bazett's equation, and the QTD ratio (QTDR) using QT/RR were calculated, and QTcD and QTD ratios were obtained. The difference between QTcD and QTDR was determined by extracting the rest values from the exercise values.
  
  
  RESULTS
  The groups with normal coronaries (n = 48), single-vessel CAD (n = 24), and multivessel CAD (n = 25) were compared. The obtained QTD parameters at peak exercise and their differences between exercise and rest were found to be significantly increased in patients with CAD (p <0.001). Furthermore, these parameters were found to be higher in the patients with multivessel CAD than in those with single-vessel disease (p < 0.05). With the parameters QTcD > 60 ms and QTDR > 10%, greater sensitivity and specificity were obtained compared with ST-segment depression. The highest diagnostic accuracy was obtained with the QTD parameters calculated from the differences between rest and exercise values. The diagnostic accuracy of the difference of QTcD > 15 ms and the difference of QTDR > 5% was relatively higher than the other parameters (sensitivity, specificity, and negative and positive predictor values are 84, 88, 84, 87% and 84, 96, 85, 95%, respectively).
  
  
  CONCLUSIONS
  The use of QTD parameters as variables of ECG, which is easily obtainable in the evaluation of exercise ECG in women, increases the diagnostic accuracy of the exercise test. In addition, the evaluation of QTD variables may provide information about the incidence of CAD.
authors: Department of Cardiology, Faculty of Medicine, Selçuk University, Konya, Turkey. kurt33@hotmail.com
authors: Kurtuluş
authors: K
authors: Ozdemir
authors: Bülent B
authors: BB
authors: Altunkeser
authors: Mustafa
authors: M
authors: Aydin
authors: Ali
authors: A
authors: Ozeren
authors: Gülizar
authors: G
authors: Daniş
authors: Hasan
authors: H
authors: Gök
mesh_terms: D000704:Analysis of Variance; D003324:Coronary Artery Disease / Q000175:diagnosis*; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008875:Middle Aged; D011237:Predictive Value of Tests; D012044:Regression Analysis; D012680:Sensitivity and Specificity