|Title:||Increased Ventricular Repolarization Inhomogeneity during Postural Changes in Patients with Syndrome X||Authors:||LEE, TSUNG-MING
|Issue Date:||1998||Journal Volume:||v.82||Journal Issue:||n.5||Start page/Pages:||615-620||Source:||AMERICAN JOURNAL OF CARDIOLOGY||Abstract:||
The interlead variation in QT interval (QT dispersion) can be used to assess regional inhomogeneity of ventricular repolarization under a variety of conditions including stress. Patients with syndrome X who may have an increased sympathetic activity and could change QT interval regionally will give rise to an increase in QT dispersion under exercise testing. To test the hypothesis, consecutive 26 patients with syndrome X ( Group 1) were included. Two additional matched groups in terms of age, sex , and left ventricular mass index consisted of 26 nonconsecutive patients with coronary artery disease (Group 2) and 20 normal subjects (Group 3) for comparisons. Standing induced a significantly higher increase of heart rate in Group 1 than in Groups 2 and 3 (7.5 ± 6.0 vs. 4.0 ± 6.3 and 1.1 ±3.6 bpm; P = 0.05 and 0.003, respectively). There were significant differences in QT dispersion between Groups 1 and 2 at upright standing ( 48 ± 12 vs. 34 ± 14 ms, P = 0. 0003), but neither at baseline (33 ± 14 vs. 38 ± 11 ms, P= NS) nor at peak exercise (38 ± 9 vs. 38 ± 9 ms, P = NS). Results did not change when QTc dispersion was substituted for QT dispersion. From a conditional multivariate logistic regression analysis, independent predictors of occurrence of syndrome X at upright standing were only QTc dispersion ( odds ratio = 1.255, p = 0.01). In conclusion, electrocardiographic QTc dispersion provides important clinical information. Patients with syndrome X had a higher increase of heart rate and QTc dispersion in response to standing from supine position compared with patients with coronary artery disease and normal subjects.
|Appears in Collections:||醫學系|
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